drivetrain- get a Vortec...so about 2000+
I have a 4.8 3 spd w/ OD in my 2001 sierra- it has over 160k miles
fuel pump, water pump, oil and filters that's it
MPG on that is about 16. rated 280 hp
I have a class B built on a 2005 chev 3500 it weighs lots.
6.0 3 spd w/ OD MPG is about 15 at 65 MPH. rated 305 HP
it has a rated towing capacity of 5000#, which could be handy.
stayed with a GM as I already understand much of the mechanics
on many of the manufactured B on the chev chassis, the 2nd door is sealed shut...mine has the fridge behind it...so vents
for a home built tips check youtube.
I would stay away from mdf- it is heavy and not as strong...screws pull out etc.
so go for higher quality wood.
a cassette type toilet will work well...if you keep it to liquids only- no solids... not even paper, it is much easier to deal with
mike