1) I have done two things, one is to stick the drivers in places that most would consider to be esoteric. The second thing is that I am building bandpass boxes for the midbass, and stuffing them in places you never thought they would go. You can do this because you can get insane output levels from BP boxes and you don't need huge drivers to get there. Also, with some thought you can work the tuning and BP peak into the problem areas and eq the rest. At least, that's the plan . But BP boxes are not easy to build, and I can assure you these are the most complicated boxes I have ever attempted.
2) People will still stick to the "IB" in the door no matter how much you argue against it. I still think it is the worst possible spot because you are literally sitting at the edge of the dipole baffle, with only felted strip of rubber between. But people swear by it.
I am curious if one can get away with just two midbass drivers for an "array" by simply placing them eccentrically with the problem frequencies in mind.
It's a complete p.i.t.a. and the main reason I bought a 3D printer.