If you are looking for midbass, I'd upgrade the amp... even the orion's would work better from 110 - 150 watts, depending on your high-pass setting.
Shallow mount, low price, low power, mondo midbass... you are looking for a miracle.
What amp do you have, what make and model?
But I never give up either, LOL!
What about going bigger, like over-sized 6.75" - 7", if it were available... could you do that? That would give you more efficiency/midbass.
And here is something else... what about a 6X9" if it was shallow enough? 15% more piston area = more efficiency and midbass.
Hey, I'm trying!