WOW!!!…Great Build!..You need to patent that.

There are a lot of pictures on his website where people have done exactly what you are talking about. My next one that I build is going to be that way also. If you ran out of gas then you must have been low when you went out there. My EZ built cart will go about a month before I have to refill it. I think I would check for leaks. [:)]

We built our cart on a flat bed cargo trailer frame (cut it down). We looked at several sites. Looked at several floor plans.  Then came up with our own design. We serve out the “back”. We built ours to fit in a 10X10 flea market/festival space. We kept it small because we live  full-time in an RV and space is limited in campgrounds. We can’t have a huge trailer taking up space on our site. 
 
I will tell you the same thing I tell everyone else about building something yourself (we are currently converting a 40 ft BlueBird school bus into an RV for full-time living, so we get a lot of “Why”)… When you build it yourself, you know how to fix what might break. When you build it yourself, you can customize it to suit you and your specific needs and wants. When you build it yourself, you can build in “upgrade ability”. When you build it yourself, you can build it to the point that it is usable and still continue to “finish” it while you are using it.
 
BTW, My suggestion to you would be to build your unit to where it can be completely enclosed at a later date. Based on what I have read on this forum for the past year… it looks like that is what pretty much every HD is going to require.
 
Our pic’s of the cart… http://photobucket.com/DavidsHotDogCart http://photobucket.com/DavidsHotDogCart

This isn’t so much a plan as it is a series of photos… this is a friend’s cousin’s build… his location is up in Vermont.  Basic but nice.
 
2.6MB Zip (about 60 pics)
 
http://rcpt.yousendit.com/971251287/b7a2777fa09e4c34f5805f8648a141a7 http://rcpt.yousendit.com/971251287/b7a2777fa09e4c34f5805f8648a141a7

As it just so happens I am just starting on building mine.  Today I bought the 40×49 red trailer from Harbor Freight.  It’s on sale for $179.99.  I also printed a 20% off coupon from the net so the trailer cost me $156 and some change (not the kind Obama talked about).  The larger one is $299.99.
 
Once I get my trailer put together I will buy the aluminum and stainless I need for the box portion and all the rest of the pieces.  I will be videoing all of it for learning purposes.  I plan to do all of the work myself. Mine will be built to serve from the side and not the back like most carts are setup.
 
I have to get the plans sent off to the HD for approval but it should pass OK as I am using all of the same material as almost every cart builder uses.
 
Several cart makers have schematics on their web sites.  Just take a look at them and you can figure it out from there.  I’ll post some of my pictures once I get the side panels.