First things first, (I didn't wade through the whole thread - forgive me) I think that a bent mouthpiece would be a good way to go to get the horn in the right alignment without screwing up your chops. This was always a problem for me while marching and I never did get a bent mouthpiece. You wouldn't be the first person to do it by a long shot either - I believe that Patrick Hession plays/played a on a bent mouthpiece. I once messed with doing that on my own with an old mouthpiece that I clamped in a vise and whacked with a rawhide mallet, but that's probably not ideal.
I think that if you get the bent mouthpiece, it will solve a great deal of your chops problems while marching because you won't have to crane your neck back or lean back to get the horn in proper alignment, and any decent brass repair shop should be able to do that for you for a small fee.