Replying to Mounting Subwoofers - Different places

So i have a 98 tahoe, and i want to put subs in it.

BUT - Im not down with just sticking a box in the back behind the back seat, because we actually use the cargo area, including folding down the second row to put multiple bikes, or wood, or rails, or whatever in it.

SO - Im wondering where it is possible to mount subs in a way that they wont interfere with any cargo space. Like - is it possible to pull out the factory ceiling mounted back speakers and cut the holes bigger and put the subs there? or where else could i put them?

++k for help, thanks