That Cummins will serve you quite well. With the weight pushing empty, a turbo should help a bit on the hills.
Did you re-enforce the frame rails to handle all that extra torque? A couple extra stiffening box beams should do the trick.
Good luck, and I'm not seeing any pictures. We love pictures.
Del & Jerre w/Isis our English Bull Terrier
The Cougar's Den
1984 Fleetwood Prowler "E"