To start with I got one of there sport bar mounted tube bags, this straps securely to the rear diagonal downtube on the sportbar and offers a fair amount of storage where no storage was before. I use this bag to hold some cold and rain weather gear since being warm and dry can be the difference between a great and terrible trip. This bag conveniently stores a pair of snow pants, a rain shell, gloves, and toque for winter, or a down jacket, down vest, rain shell, gloves, and toque for summer. I would have thought that this bag would be prone to flopping around but it seems to stay well in place at least with the hardtop on.
Typically I use these rear bags to hold my maps, on the drivers side, as well as my girlfriends spare clothes on the passenger side. They hold there shape well, making it a perfect compliment to the rear shelf and Dometic Fridge.
Below are Amazon affiliate links for both of these bags. By using the links below it helps me get a small kickback from your purchase while you get the same great prices and service from Amazon.
4 Door JK Side Bags
Rear Roll Bar Bag