buying cargo van vs. box trucks

Greetings,

I live in upstate NY and am looking to purchase a vehicle to convert into a camper. I have no experience with building such things (but have reasonable carpentry and electrical skills and am not intimidated by things like sawing a hole in the side of a truck, LOL).

I can probably adjust my desires to almost any size, but height is non-negotiable; I need to have room to stand up. I am 5'4" so I think a high-roof Ram Promaster, a Transit, or a Nissan NV could do.

But here's the problem: there are not many of these kinds of vans in inventory locally. I can find them in ebay, but then I am dealing with purchasing a van several states away and have to deal with hiring an inspector to take a look and so on.

I had been dismissive of converting a box truck because they are likely more difficult to drive, burn more gas, and are less aesthetic from the outside. However, box trucks from rental fleets are easier to come by. Fleet trucks will have been well maintained, for sure have a single owner, and full maintenance records. And, if I get one in my own town, my own mechanic is around the corner. There is enough space to put in a shower/toilet with less of a space struggle than in a van.

So my questions are:

• In general, aside from availability and price, what are the tradeoffs of building on a cargo van versus box truck platform;
• I am seeing 2008 - 20014 GMC-based 14' box trucks with about 170k miles for around $10k; does that seem like the right price point?
• The site for these outfits says "Call to make an offer"; I suppose I could get some idea of comparables from looking at kelly blue book (if it lists box trucks) or ebay, but I am curious as to how far down one could negotiate (it looks like some of these have been listed for a while).

I am grateful for any thoughts on these and any other topics.

Thanks!