I am not prepared to offer any advice as to the legality of the "camp" situation is as that is completely in the purview of local governments and codes. If this is in one of the police state of the coasts (East and West) it could be an issue.
But, as to a cell phone "booster". There are more than a few good ones on the market. I have almost always installed (for others for $) and used for my own things that were made by Wilson Electronics. They now market as Weboost. I suggest that you go to
Weboost and look over what they say. You don't have to buy theirs to get good advice. I would not be without one when we travel. A lot of this country does not have good coverage.
Matt
