Let me preface this comment by saying I in no way consider myself an expert on trailers but as my private mail is nearing the max of 200 and they are all asking about the same thing, here goes;
I found my body on craigslist. I paid maybe $350 for it. Knowing what I know now, for a good fiberglass body, I'd spend up to a $1,000. Getting the right body is essential. As well, I'd buy it almost anywhere and consider the journey to getting it home part of the fun. I still look for bodies on occasion. I search for terms like service body, utility bed, etc. I dont search using 'fiberglass' as often the best buys come from people who have no clue the materials. They just want it gone.
IMHO, a full size body is too big. If its purpose was for a family to venture along maintained roads and spend time at camp grounds AND you had a V8 or diesel, then perhaps. But they'd be too big to wrestle back into the sticks. And too heavy to man-handle when those switchbacks and deadend trails require disconnection.
Old bodies from the 'minitruck era' are my preference. Mine is only 7' long. I think its from the mid-80's when Toyotas and S-10s were in style. The fiberglass body is lighter. Mayby 50-75% of the steel body. But its also very easy to modify. I dont see many for sale and most are up in the northeast regions.
I think
Dinoot Trailers is on to something good. I'd bet they introduce something akin to a utility style body soon. But for sure you could modify their current model. The ability to start a trailer build with a light new tub is appealing, especially if youre pulling with a V6. If I didnt have 70 odd project all needing my attention, I'd probably build another trailer with their tub. I'd add a front compartment for the fridge, and put alum boxes on a rack above the tub to simulate a utility body. It wouldnt hold as much but I know it would be functional and durable, and fun to build.