I think i am sticking with plan C! Instead of modding the "plan A and B" box to fit the 15, i said "f#$K it" and built it all nevw from scratch. This time i used all 1" with exception of the bottom board (due to fitment issues). Its ok though, the bottom board is on the floor of the trunk so its plenty thick. I will probably do some glassing as well. This will be a LONG build so hang tight i cant do it all in one day!
FYI: all RF amps and hopefully 3 sets of T5 components to go with this...
Time to cut the port. It has 51" of area. It is 8.5x6" and 14" long. Tuning 38hz.