I can relate to your "love" of motels/hotels. My work in the past had me living in hotel rooms for up to 3 months at a stretch and I grew to hate it. I had a perfectly good converted bus sitting in my driveway at home and was stuck in a hotel room. Eventually I managed to get the boss to let me drive my bus to jobsites. It was AWESOME traveling the country in my own home, sleeping in my own bed every night. That lasted about 6 years. Loved it.
I too considered the semi tractor-trailer conversion option. Two considerations steered me back to a bus.
First was cost. I fount that I could get a bus with 150-200k miles for a fraction of what I would pay for a tractor with 700-900k miles. Decent trailers were almost as expensive (when I looked) as a bus.
Second was flexibility in where I could stay in it. It doesn't sound like this is a concern for you.
If your budget will accommodate a tractor-trailer in good shape I think it is a great idea and much of the info available here regarding bus conversion would be equally applicable tp converting a semi trailer.
I think a great candidate would be a refer trailer. Already well insulated and, if the refer works, air conditioned
.. Really, with a little modification I think you could have a diesel powered 12v battery charger and air conditioning from the refer unit.
Regarding your current buses; Those sound like nice rigs. Mechanical DT466, MT643 & 4.44 gears. Plenty of folks here that would get excited about that drive train.
Best of luck on your project and please post pics here.