If it's just you and your pooches, I would recommend building a platform for the rear cargo area for the dogs to ride on top of, and then you can put gear underneath that. If you combine that with a larger rack, you should be able to carry everything and then some.
I built a shelf for my dogs (a lab and a small coonhound), and they ride on top of it happy as can be. You can kind of see it in this photo-
FathersDay2016DSC_0016 by
scottybell1313, on Flickr
With that shelf and my 10 cubic foot box on top, I'm able to get myself, my wife, my two sons, my father-in-law, 2 tents, 5 sleeping mats, 5 sleeping bags, 5 camping chairs, 1 48quart cooler, 1 5 gallon water jug, dry goods, axe, shovel, and two dogs and more. We look like the freak'n Clampits rolling down the road, but we get there.
When the boys get bigger (they are 4 and 6 now) we will likely get a trailer and a larger roof rack... but for now, this works.