Yes, exercise pens can and are commonly used at campsites and are a nice alternative to holding onto a leash 24-7.
HOWEVER, PLEASE DO NOT leave your dog(s) unattended in the pen, even for a moment.
The first, most common, reason is that unattended dogs are more likely to bark. If neighboring folks hear your dogs barking (whether or not it's excessive barking) and they see your dogs outside in a pen with no person in sight, they are more likely to complain to management, etc.
Also, as Johnno02 indicates, just because your dogs are well-trained and stay in their pen doesn't mean that other dogs will abide by those rules. All it takes is a couple seconds and your dogs could be in serious injury. Exercise pens are not constructed to provide unattended security for your dog.
And that is the number one issue with electronic (aka invisible) fencing. It only works on the dog wearing the collar (YOUR DOG). There is no fence keeping unknown loose dogs out of your space - thereby putting your dog at risk.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)