What would you do?

Awhile back I bought a 94 3000Gt for a decent price. Yes, it is a Base model, you can laugh now. BUT! I love the car.. The only problem is, I love car audio. The problem with me loving my car, and car audio is, I can't put anything in my car due to the lack of room. The car is small enough already, but I currently have 2 12" subs. The box is something along the lines of 30" Long, 18" deep 14" tall, or close to it. The point is, I can't put it in my trunk because of the spare tire, take the spare tire out, and there is still a mold from where the spare tire fits, so it's pointless. What i've had to do is lower my back seats down, and set my sub box in my back seats. It works.. But I don't like it. I really want to feel like I have SOME room at least, and would like my back seat back.

So heres my problem.. I don't think it's possible what so ever to even have someone build a box for me for 2 12"s. Because the space I have can't be any taller than like 15" taller at the tallest point, and 9" at the lowest because the truck wont close..

I think What is going to have to happen is.. I need to sell my 12's and get a Decent pair of 8's or 10's. I was really wanting to get 1 or 2 FI SSD 12' subs, but that probably wont happen. So my question is.. should I get a couple 8's, or 10's. I've never had ANY experience with 8's nor even heard them, and have no idea how they compare to 10's or 12's.

What would you do in the situation?

Thanks guy