well im not sure if this is mystery solved, but i went into a local car stereo shop today and asked about how to solve this problem us base/nismo owners have. he said one sec...and came out from the back with this:
he said they just trim these to fit any stock openings. not sure if its problem solved for us yet..but i will take the dremel to this shortly and let you guys know how it works out. he charged me $5 for it (quite expensive if ya ask me), and its only a really thin piece of plastic with some clips on the back, but i figured id rather just pay instead of searching high and low for another solution