BOZ22N,
I am not familiar with the amount of space in the battery and fuse compartment (newby to lines), but if you can fit the speaker in there you can probably mount them there. Boxes can be made very small (to just fit the speaker) especially for 10's. You will have to port the box/s (make a breather hole) which allows the speaker to act like it actually has a larger box area. BUT, this has to be done properly, with proper porting diameter and lenghts. You can buy adjustable ports from places like Jaycar, Dick Smith etc, and your subs should have come with some info about box sizes for enclosed and ported (not sure if it gives porting values tho).
Which size amp are you running? A ported box will mean you will need a little more power, but not anything too over the top. You might also want to look at mounting the two subs back to back (one facing the boot, one the driver) but this means you will have to change the phase of one of them (preferably boot facing one).
Other than that you can get into making wierd box designs and stuff if you really want to save space. hope this helps