Great post and thanks for sharing your experience as that helps us all.
I’m probably not the best person to advise you on this as I have struggled with shallow mouthpieces. I did get a Bach 3E to work for a bit, but found a C cup works better for me. I even found that my range improved when I went from a 3C to 1 1/2C, which doesn’t make sense but is what works for me.
Options b and c above seem to make some sense, but option a seems like not a good idea to me, I’m afraid you’ll wind up tensing your lips and manipulating too much.
I think the only engagement we want is outside/around the vibrating surface.
I would suggest not worrying about not being able to play a certain mouthpiece and just play whatever sounds /feels / works the best while you develop your range.
Greg and all the greats say they can hit the same notes on Any mouthpiece, but certain mouthpieces make it a little easier / more efficient.
My $.02, FWIW. If you do figure out how to play a shallow piece, please let me know. Good luck!