This is the reason for boarding facilities. A subject I have strong opinions on. You could either board them at your home vet or clinic or make arrangements ahead of time at a facility near where you'll be camping. If they could stand a bath or grooming, find a Petsmart or similar and that'll take care of one day.
By the time you invest in some gadget that may or may not do its job, you could be assured they'd be cool and cared for. Another option would be to see if your vet could recommend one in the area who might be able to connect you up with someone who would come to your campsite and be with the dogs, walk them, etc. I know there is expense involved, but figure that into the cost of this trip as an essential, which it is. No activity is worth coming back to a tragedy.
