That’s 3-4 hours away, IE a 6-8 hour drive every time someone is done renting it, to clean, change bedding, fix stuff etc. And generally most rentals will be for the weekend or through the weekend so that will be an after work exercise during the week virtually every time.
Possibly more effort than the first plan of delivering it to random locations. (Which would require a second driver and vehicle to bring you back.) Or you could drop it off the truck each time which = more time spent each time.
And you’re putting personal “mods” in it like the diesel heater which will not be conducive to renting to the general public. Like renting out an old hot rod vs a new Toyota. You’d have to have the right person who knew what they were doing or risk further damage and issues.
Renting it with the truck turn key, imo is a non starter all around. Way too risky. You can’t screen clients enough to know whether they can drive something they’ve presumably never driven before. (And more insurance requirements than necessary if it’s effectively a portable cabin with no vehicle involved in the rental).