Last year I bought a Custom Mobile “525” cart. (not a pushcart, but a towable cart), I use an SUV to move it around.
The manufacturer is in Hammonton, NJ – so I was able to visit their shop before I put any money down. These folks have been in biz since the fifties and they make full blown mobile kitchens for the red cross, FEMA, and hollywood caterers – so a hot dog cart or vending trailer is childs play for them. Standard equipment includes your 4 sinks (one handwashing, and three for wash/rinse/sanitizing of utensils. It features pilot burners (for safety – if the flame goes out, it shuts the gas off) and a separate burner for the hot water (rather than a coil of tubing around your main burner). The heath dept. was impressed with the that. It has a lockable bread drawer on roller bearings, and hinged covers on the steam pans. (nice TIG welding) I needed to add a food prep tray and that’s about it. It did cost quite a bit (almost 6K) but it is built to last. I was able to pick it up myself, but they crate them and ship them all over the country.
Maybe try and find one of these on craigslist and save some bucks, they pop up every so often.
-Trent (a professional hot dog vendor from Trenton, not a self taught chef from an undisclosed location)