The other observation I'd pass on is the experience of a buddy of mine who spends a lot of time camping while hunting & fishing.
Since he goes into some pretty tricky spots he didn't want a 'glamour queen' nor did he want to spend a pile of cash. The solution (he thought) was to convert a shorter school bus built on an International 5 ton chassis. Everything went quickly & smoothly.
He was very happy with the finished product, until that is, he took it for his first 'shake down' drive. The chassis had been spec'd as a 'city' bus, not a 'county' bus. It had no overdrive and pretty deep gears in the rear end. At 50 mph (80 km/h) it was screaming and sounded like it was going to fly apart!!
It ended up costing him nearly as much to swap out the transmission and rear final gears as the entire thing had cost to-date!!
An expensive lesson indeed.