NEED Speaker ideas for behind the seat.

[GMR-PERFORMANCE]

I have not alot of room after the 03 tahoe seats are in and the NOS bottle. But I noticed that there is a bit of room in the cab corner area. Has any one built a custom speaker encloser for say a 6 X 9 or the now popular 6 inch round?? The gap is not big enough to fit in but if it where say one inch out you could use that area for the encloser with maybe a simple cut sound board to fit and hold the speaker.. Not looking to make this truck a sound system unit by any means. Simple alpine head unit and will buy the kick panel units with the speakers in them. Would like to add 2 more to the rear and call it good.