I am in somewhat the same boat, liberal arts education, been with my previous employer a long time, hoping to break out of my specific niche, and wanting to avoid relocation. It should be noted that I haven't found a new job yet, so you may want to take this with a grain of saltshaker.
I've switched from a traditional reverse chronological resume to a skills-based resume in the hopes that it helps me make it past the initial scan. The thought is that if you list your relevant skills first (including the right catch phrases and buzzwords for your industry) and put a work history below, it minimizes the chance you will be quickly rejected for what seems like irrelevant previous job titles or in my case, a work history somewhat unrelated to my desired position. I've been looking at job listings to get ideas about how to refine what I highlight on my resume for the types of job I desire.
The biggest help I've found so far has been from a book called the 2-Hour Job Search by Steve Dalton. The title is a bit hokey, but much of the content is good. It is helpful because it is all about networking and job hunting in the modern age, and is geared towards folks just out of school or folks looking to make a change mid-career who are struggling with networking and feel like they are just throwing job applications down a black hole with no progress. I skipped some parts that were more focused on the recent graduate, so I didn't do it cover-to-cover. Here's what I've liked best about it in a nutshell. I'm not going to become a pusher for the book, but my take might help you with some ideas:
He points out that limiting yourself to big companies severely limits your prospects because there aren't very many big companies out there, and they receive the most applications. A business with more than 500 employees is high-profile, and assuredly has a careers section to their website where you can fill out an application online. The ease of applying and high visibility mean that everyone and their grandma is applying, hence the warning about follow-ups, so by applying you are jumping into the biggest pool filled with the most sharks. Yes, a bigger company likely has more openings than a smaller company, but the lion's share of the total openings in the market are at small companies, they are just more scattered. He asks, "Why limit yourself to a small portion of the job market, and the most competitive one at that?"
A smaller more local business (50-500 employees) is not as visible, may not have online web-form applications to fill out, and there are exponentially more of these types of businesses than the big guys, so focusing here takes more work on your part, and may not seem like a certain future, but it is a very quick way to become a much bigger fish in a much smaller pool.
The other thing I appreciated was the way he gets you to think about things from many different angles, and as a result, got me thinking about some employers I would not have considered otherwise. Early on, he encourages you to generate lists of potential employers WITHOUT doing any more research or filling out applications. It is just brainstorming, so clicking through to more details or reaching out to contacts at the company bogs you down before you have applied any filters. He has you make your lists without worrying about specifics, then start applying filters later to quickly narrow things down. For example, name some dream employers, add them to the list, then maybe jot down any competitors for those dream employers also. Make a quick list of companies at which you have a contact, personal, professional, or alumni...don't worry if they have any openings at this point. Instead of focusing just on your preferred industry/job title, spend a little time listing other companies that offer a similar corporate culture to some of your desired jobs. Do a few quick web searches on trends in your desired industry and see if any companies pop up that you haven't listed before. Change one parameter at a time in your job listing search (widen the pay, widen the geographic area, go up one step in specificity of job title, etc) and see if anything new pops up you hadn't seen before, etc.
Once you have a big list, then he has you put them through the wringer of more searching regarding pay, location, current openings, potential contacts on LinkedIn, glassdoor.com, indeed.com, your alma mater's career center, etc.
He also encourages you to seek out informational interviews as a way to add new connections to your network and cast your web further. This also takes time and effort, and you aren't likely to have success if you think of it only as a stepping stone on a linear path to getting a job. It may take time to see the dividend of this type of work, and the opportunity may not come from the company in question. Even if they don't have an opening, if you are genuinely interested, and can find/build some connection to someone at a company, that gives you a potential in to ask for a chance to chat. If you come prepared with questions that demonstrate an interest and showcase your knowledge and skills, and aren't just angling for a backdoor to a job, it may lead to a heads-up about a job opening at that company down the road, or might lead to a suggestion you reach out to a contact of the person granting you the interview, like, "You might want to talk to my college friend/former boss/brother-in-law who works for Acme in the next town over" or something similar. These interviews can also alert you to weaknesses or question marks in your skillset or the way you present yourself and can help fine-tune your resume or bolster future interviews at another company.
The last bit of advice I got was not from the book, but from a friend into cars. He suggested reaching out to any lawyers, bankers, and accountants I know, especially ones at smallish-to-midsized local firms that offer services to commercial customers. The reason being that someone in these fields is likely to know when one of their customers is looking to expand or going into a hiring push. If they know you are looking in field XYZ, they might be able to give you a heads-up about opportunities likely to be coming down the pike. I went one step further and did the same with some acquaintances who are super-outgoing busybodies who also have a bit of social-worker streak...if they know I am looking they become an extra set of eyes/ears out there for me.
BTW, if anyone still reading has information about corporate training and related HR work for a guy looking to expand upon what he's learned in his career to date in sales/retail management, I'd be much obliged.
Hope this helps, and good luck!