My one Siberian could pull a picnic table around by herself, so three could easily turn it into a high speed sled - good for laughs, but not so good for camping :) I'd be sure that you pick something a bit more immobile, or at least test it out carefully first.
Also, be sure that whatever claps or fastener you have on the ends of whatever you use is seriously solid. My Husky could break most medium sized lead clasps when motivated (by, say a rabbit, deer, racoon, etc., any of which can be easily encountered in a campground.) so three are going to put some serious strain on whatever you use.
And, before someone mentions proper training, being well behaved, etc. a Husky is not truly a pet, they are more a working dog with whom you develop a general understanding, and no amount of training can fully overwhelm their instincts (this from my vet, and it proved very sage advice...)
