That is a terrible idea and you should absolutely do it!
Downsides:
- It's already pretty much overloaded
- The frame may have been extended to the back
- Van engines are a PITA to work on and the older the engine the higher the likelihood of work
- RVs can be a maintenance n*i*g*h*t*m*a*r*e
- "Can be"!? WTF am I saying. They ARE a maintenance nightmare...
- Finding a place to store and work on one can be an additional monthly expense
- Not every place that will let you store the unit will also let you work on the unit there
- You're absolutely right in that you will stop at basically every gas station
- Not the easiest thing to drive in wind
Upsides:
- Waking up in the paddock in your own bed, using your own bathroom, taking a shower, and having a cup of coffee before ever setting foot outside
- Going inside to the air conditioning on a hot day and eating your lunch in comfort
- Don't want to make the whole trip in one sitting? No problem, stop pretty much wherever you want, no need to unpack and re-pack, just have a meal, suck down a beer, go to bed, get up the next morning, take a shower, make some breakfast, hit the road
- Weight of the rig means your trailer's manners will become mostly irrelevant
You do you, but in my opinion the benefits of the upside of this Schwartz totally outweighs the downside!
Check the underside in the back. Many manufacturers took the stock chassis from whomever (Chevy in this case) and if it wasn't long enough affixed frame extensions to the existing frame rails. This wouldn't be a problem except for the fact that they usually took a bit of C-channel and butt welded it. And by "welded", I mean that they hired a blind man who never touched a welder before and was only vaguely aware of the principles of attaching bits of metal to other bits of metal and gave him about 15 seconds to attach both rails. The problem that you'll run in to is that the force on the trailer hitch will travel from the ball to the tongue to the receiver tube to the hitch to the frame extensions but the craptastic welds will not be able to effectively transfer that force to the real frame. That will cause those extensions to break loose and sag causing a best-case of simply causing the back cap of the RV to separate from the rest of the RV. Worst-case, of course, is that the extensions tear loose and join your trailer on a new adventure where nobody tells them where to go! The fix there is to reinforce the frame extensions with some additional C-channel on the inside to ensure that the forces from the trailer get communicated all the way to the actual frame.
Once you've fix that, though, now you get to be a mechanic-plumber-roofer-HVAC tech-carpenter-electrician-appliance repairman as you chase after the things that will break. The roof will leak if it isn't already, and water has other places it can get in as well. Your appliances are old and go banging around down the road, so they will need attention from time to time. Mice and other undesirables need to be kept out, and there's the winterization dance you need to do every year. Tires will typically age out, although on an older C-class van chassis they shouldn't be too spendy.
All that said, though, it is so nice to be able to stay on-site and have your own accomodations. It is nice enough to make all that other work absolutely worth it.