I'm worried about the bass guitar reproduction, I want quality
bass at high spl to mate with the above midrange/tweeters.
Initial thoughts are to use a 15" or 18" prosound woofer in a sealed
box for good bass, but doing so I lose the low end response (20hz-30hz).

So.. I don't mind building an additional subwoofer to
complement the system for those home theater times when you want
to shake the intestines.. Is this the right choice or should
I combine the woofer and subwoofer together ? Doing so, I probably
have to sacrifice quality ?

The last issue is the midbass. The midrange will probably be crossed
over at 300-400hz so I need another driver to run between the
woofer and midrange. Again, my initial thoughts are a prosound
12" in a sealed box (f3 80-100hz).

I plan to use a fully active crossover system for whole cabinet.

Any thoughts on driver selection and box configuration ?

My brain has odd ideas;

Plan A = one tweeter, four midrange, one prosound 12 inch, one
prosound 18 inch in a sealed box (per channel). F3 probably 60hz.

Plan B = Plan A plus a seperate subwoofer enclosure using a long
throw 18" subwoofer to complement the system. F3 probably 20hz.

Plan C = Compromise, combine plan A and B and use the 18 inch in a
vented box to extend the low end from f3 60hz to maybe 35hz (heh)
and lose transient response of a sealed box and lose 20hz capability?

Plan D = Plan A minus the prosound 18 inch woofer.. Instead use
a long throw 18 inch woofer in a vented box to reach 20hz. Make the
12 inch midbass work a little harder perhaps cross them over between
80-300hz and hope the bass quitar will sound good ?

I'm limited to 10 cubic feet for the bass cabby.