Does anyone have experience running speakers in parallel on a Harley amp? I guess you could run the left upper and lower on one channel and the right upper/lower on the other, but I really don't know if the Harley amp can handle it. Honestly, I would be surprised if it could.
So, I guess the lower fairing housing is one issue- is Hogtunes the only company that has cracked that nut? I know other companies, like fairing factory sell seperate pieces, but that is not a good solution for your bike.
The other issue would be having an amp that could push the extra pair- I'm guessing you would either need another two channel (takes lots of space) or a 4 channel amp to power the three pairs you are going for.
The best advice I have- find someone smarter than me on this issue. That is all.