I haven't had a chance to read through this tread in it's entirety yet and I'm sure you got lots of great advice so far but I'd thought I chime in w/ two cents anyway.

My pup comes along w/ me every time I head for the trail as long as I'm not visiting a restrictive park. As far as being inside the tent, he hasn't been much of an issue. He does have long nails(I leave them long so he has a better grip climbing steep terrain) but our tent is so snug that once it has two bags in it there isn't much tent floor exposed. If he's particularly dirty, I put down a small pack towel in the vetibule and he's pretty happy w/ it. He's only 35lbs so he fits well.

I bought him an REI dog pack last year and it's worked out fairly well. W/ this he can carry both of his collapsible food and water bowls and about 5 days food. The pack isn't close to waterproof so keeping the food in a couple of 2 liter Sea To Summit dry sacks is what I've had to do. Ziplocks just weren't cutting it. After a jump into water, shake and roll in the dirt, the bags would bust open.
Also the pack would have to have balanced loads in each side. The straps like to slip when wet and soon the pack would dip to one side. I'm sure this is uncomfortable.

You might want to get little booties as well. After a long day for the pooch on rough terrain, unconditioned pads will become raw and irritated. My pup would show reluctance w/ these at first but I'd slip them on later on in the day only when I had to. The REI ones could be a little finicky too so you'd have to keep an eye on them. They might fall off if not put on correctly.

And last, rattlesnakes are always a concern on hot days in rocky areas. If you have a particularly rambunctious or inquisitive pooch you may want to keep them on leash in these conditions. There is a rattlesnake "vaccine" but it basically only works to slow down the effects of venom long enough to get them to a vet. Unlike most snake bite regarding people, they're most certainly a death sentence for dogs. And if you're out far enough, a vet is out of the question.

I think in Virgina you guys have Cotton Mouths? Maybe Water Moccasins? Either one, both are worse than rattlesnakes.