Miata install with pics, and problem

ok this is the box and rubber gasket i was talking about, please feel free to say what you like i love the opinions.

BUT my problem is here....

this is the way the car came to me..

this would be the first stages, sorry no in between pics, but with such a small trunk this car needs all the space just for the 2  - 10"

next is the outer trim i made.......TIME CONSUMING, never again...lol

the trim snaps in and looks tight.......but

with the owner taking the car all the time and i found myself making this without the car 90% of the time, due to that i made a huge mistake........

i filled in right to the top with body filler, the box is now really smooth but at the top it is too thick to get the rubber trunk gasket over it and the steel lip.... so what do i do??

i cant grind away the body fill casue in some parts it is 1/4 inch away from edge.. like in photo below

all in all i love the look, the amp is going to be floating in between the 2 subs with lights under it...pics coming soon as problem solved...lol

soooooo let me know how to fix this F*%k up!!!! and let me know what you think.

I am confused as to why you can't just sand down the body filler.  I understand the 1/4 gap in some places, so you can't just uniformly sand all the way around.  But if you went slow and sanded little by little, I don't see why it wouldn't work.  I would lay the rubber surround around the opening and mark it with a pencil, and then sand it.  The other option would be to trim the ring to fit barely under the flange of the rubber gasket.  If you can think of another way to dsescribe so I can btter understand you and have an "ah ha" moment, I'd be happy to give it more thought.  Over all I think it looks really awesome.  The floating amp will be really cool.

well part of the prob is that it has cured and moved in and even if i sand it to the glass in a few spots i will be still 1/4 - 3/8 away in some spots.... but i am thinking of adding some layers of glass to the back in the spots that have lifted and then i could sand..... ah ha.... i think i got it lol

Yes, this is what I do to make my projects fit tight up against panels & liner's.