Towing any high walled RV is hard work on the truck with all that wind drag. So going lighter helps a little, and more so with hills.
Now 900 pounds of tongue weight on 14 year old leaf springs with worn out shocks might not be fun either. So evaluate the condition of your truck to make the best judgement.
4-spd trans with 3.42 axle means 3 usable towing gears. Are you willing to change to 4.56? 4WD truck will cost more for both axles.
Or, your truck is worth something. A similar vintage 3/4 ton big block will more comfortably tow pretty much any TT at not much more cost than the value of your current truck.
Just listing ideas. You may find the combo acceptable for a while to do anything.