Sorry to hear of health problems. My wife is going to be using a 3 wheeled scooter this year, to get around in the campground.
Both the trailer and truck should be easy to sell. I think I would list them to sell separate, but have the option for a better deal, when purchased together.
I doubt a beginner would want that size FW, and someone looking to move up may have their own capable truck. IMO, that truck would sell very quickly!
It is hard to get a dealers price, for our RVs, but I'd check to see what dealers are asking, compare that to wholesale value, and try to stay in the middle.
Best of luck to you and your wife.
Jerry