I think I forgot to turn the master switch on once, and forgot to prime it once. No big deal when taxying, but I certainly wouldn't recommend it for flying.
FFF,
Difficult to get flying if you don't switch the master on or prime a cold engine. You soon figure out the mistake when nothing much happens up front.
As for the trim, do a left to right cockpit check of all the knobs and instruments. You won't miss the trim -- it's down there below the mags and carb heat and fuel selector, just above the flap lever.
Much better than a written checklist in a Super Cub, IMHO.
QDM