Brett, check these pics out....
Attachment 26180Attachment 26181
When the rear storage trays are in, the ballast bag fills to the very bottom of the tray. So no lost space between top of bag and bottom of tray. There is obviously some room under the gunnel to the side of the tray, but when you see how deep these are in person, I don't think you will complain about lack of storage. As you can see in the one pic, there is plenty of room for the AO stow and go cooler. I think you can keep plenty of beers cold in there if you want. I don't know how much the tray will hold, but I did stand up in it and I am about 190lbs. Like I said before, it is really designed to hold life jackets and ropes, but if beer is more of a necessity, it will hold plenty of that.
As a side note, you will notice in the picture there is a little ledge and we have mounted some eyelets on this one. This is the R&D boat. The eyelets are not on standard production, but we have toyed with the idea of straps across the ledge to hold lifejackets up or to play with dividers. Anyways, just playing around constantly trying to come up with new and better ideas...
Hope that answers your questions.