IMHO the best bang for the buck would be a Ford chassis with the V10 built after 2006. Better horsepower and towing rating. Not to mention the upgraded transmission. Plus you have OBD2 which will allow the use of a fuel monitoring system.
At twenty years old, you'll be hard pressed to find a used unit that has been owned by one individual that has completed all the maintenance. You will usually find two or three owners that may or may not have properly maintained it. The last owner may have done a great job, but what about the others?
Without proper history of maintenance, to have piece of mind that you won't be stranded on the side of the road you'll want to go through the entire system and replace all belts and rubber hoses. Rubber hoses not only include radiator and heater hoses, but also rubber brake lines, and most people don't even think about rubber fuel lines, including the generator. (Found mine leaking just inches from the exhaust pipe on a fuel stop.) Oh yes, forgot to mention the rubber dust boots that are on the brake caliper pistons. When I compressed mine while changing the brakes... they crumbled and fell onto the ground.
I can almost guarantee you that the shocks will be worn out and the sway bar bushings, hopefully not front end components but have them checked to make sure.
I know you said that you are handy, but if not these items can cost you thousands of dollars to repair or update. Money that could be put towards a newer unit. But every unit is unique and has it's own history. I'm not trying to steer you away from an older unit, I just want you to be ready for the reality of owning one. Hope this helps.
Doug