I did some actual studying of the rear suspension on the bike I plan to salvage parts off of and realized just where the pivot is located. Never really looked at it.
You mentioned mid drive which set me to thinking about one. Using a mid drive on this Street Fox would eliminate using an idler pulley plus I could add a second gear change for really low gears LOL.
After it straighten out my garage (just built more shelves) then start carving on the donor bike.
As for using a 20 inch wheel, if I go with the 26 inch AND the mid drive, it could be a very good mountain climber and a fast trike.
Thanks for the input.