Making a steerable cart from scratch, how do make the steering?

My wife gave me a nice AC/DC inverter TIG welder for my birthday 3 years ago and I haven't learned how to use it.  I want to learn to use it for both steel and aluminum.  I'm quite good with a MIG welder, but want to learn TIG.  

Also, I have a need to make two steerable carts, neither of which require perfect fabrication skills, so this seems like a nice symbiotic project list.  One cart is going to be for fueling at Lemons races, so it needs to hold 4 fuel jugs, fire bottle, etc, made from steel likely and potentially towed by a scooter when not pulled by hand.  The other is going to be a beach cart for my in laws to bring their stuff on the 1/2 mile walk from the house to the water's edge, this needs to be made from aluminum and will likely also be powered at the rear axle eventually.  Avoiding sand and water getting into things is critical on this one.  

So, as I am trying to design these in my head the one thing I'm not sure about is how to make the steering, especially on the beach cart.  I need a spindle, steerable joint, some sort of ackerman and adjustment for toe.

I figured that someone here had made something like this before.  What did you use?  How does your design look?  How well does it work?  What would you do differently next time? Is there a kit that you have used or go kart parts or anything like that?  I'm quite comfortable with medium level fabrication, but don't have a lathe or mill or anything like that, nor any real interest in getting one now.   Thanks for your suggestions!

Edit: mods, can we change the title to add an "I" after "do" so it makes more sense? Thanks.

I see a lot of yard carts where the steerable end is like a T with the front axle being the top of the T and a pivot in the middle.  Crude but effective.

For the fuel cart you could just use  8 in. Pneumatic Swivel Caster from harbor freight under the front and none pivot 8" Pneumatic castors for the rear (think shopping cart).   With a handle/ tow bar out the front, it will follow you fine.

this one seems to have steering spindles for inspiration:

Habor Freight 1,000 lb. Mesh Deck Steel Wagon

And below is the shopping cart I modified to carry 20 gallons of water and groceries down a gravel driveway with swivel casters that works great for swivel caster inspiration.

For a powered dune cart, I would figure out how to use garden tractor axles with an aluminum frame and adapt a 48 volt electric DC motor with (4) 12 volt garden tractor batteries hooked up in series.

Bing.com: 48 volt DC motor