Hey James,
It's pretty much whatever works for you, although I do pretty much what you do. Cleat the main with the sheet not quite as tight as sailing tension so the boat doesn't heel, sit down in the harness, push off with my forward leg and then sheet in to insure that I don't tea bag.
:^ ) You're right . . . . it's much more comfortable than sitting on the tramp (I know because I have a sciatic condition), the boat's faster and you can navigate better.
I usually go out and come in aft my bungee and I encourage my crew (when I have one) to do the same. When I'm on the wire, I position myself wherever my weight gives the best boat trim.
The bungee on my boat is anchored to the hull about a foot and a half aft the shroud so when I move, it doesn't.
Also, because I found it difficult to acquire leverage from the standard trap wire length, I had it shortened 5 inches and now I get great leverage. I don't think an adjustable trapeze will help your handle height.
Hope this helps.