MargaretB,
Here's a couple of ideas to make it easier.
1. Heavy chains? If you're referring to the safety chains between the trailer and truck, go to you local RV place and they can replace them with cables like they use to secure cars behind motor homes. They're a lot lighter.
2. I'm not sure what you mean by getting underneath the truck? I never have to get under mine.
2.A If you mean to hook up the safety chains, then replace them with cables (above).
2.B If the chains are using those "C" style clamps that you have to screw the ends close, buy the above cables with hooks that have the safety snaps on them - a lot easier to use.
2.C The trailer electrical cord can be inserted when kneeling - see #3.
3. For all of my kneeling, I use a very good kneeling pad like this.
Kneeling padThere's lots of them out there that are cheaper, but in this case you really get what you pay for, your knees will thank you. I also have a much larger one for when I have to lay under the TT or DP and do repairs.
4. You talked about "manhandling heavy WD hitches" - why are you doing anything with it? Leave it installed in the truck - maybe take it off for the winter. And then, ask a neighbor for 5 minutes worth of help or pay one of the local kids $5. We always have a Rent-A-Kid in the neighborhood. If you're taking it off when you get to an RV park - don't. Yes some states have rules about leaving them on, but I'm not about to take mine off. If what you were referring to was the WD bars, then there's not much you can do about that.
5. The reason your for-sale post was deleted is because this forum doesn't allow for-sale posts - simple, it's in the forum rules.
Bill