I put CDT 6.5 inch woofers in the rear shelf. I had to do a little trimming to accommodate even those. The depth wasn't really an issue and would be fairly easy to overcome, it had more to do with the width of the top opening relative to the speaker mounting points. With some pre-fitting and a little trimming you should be able to get your speakers to mount properly.
Another consideration will be the space requirements between the stock speaker grill and the top of the speaker- rubber surrounds, woofer movement, etc. I JUST had enough room for my speakers without having to adapt the mounting depth for this clearance.
Good luck, and I am curious to how it all works out for you. Keep us posted.
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