Electric trike, anybody use one?

I would think you risk greater injury on a bicycle going up a trail with gear than you do walking. I'd also say if you are in a condition where walking is not feasible, then get an atv. If your knees are up to it, I'd suggest getting a gravel bike and start riding and throw rucking into the mix. Good luck.
They make electric 4 wheel rigs that work off road. MUCH better idea than a 3 wheel version. Just a couple of examples. Google will find a ton for you.

Rode the first Honda trikes that came out when I was in my 20s, dangerous as hell but young a stupid so got away with it. I am nearing your age now and still use a Honda gas Quad, probably will as long as I hunt as it is great for hauling out game. Not to sure the electrics would do that very well.