Although you asked this question years ago, perhaps I can still help, or help others in this same situation. I'm using a wireless adapter to get to the free wireless at a distance. It connects to my laptop with a USB. I have found the solution to this problem of friends or family wanting to connect to the internet while visiting. You can actually turn your laptops normal wireless antenna into a wireless router! The wireless adapter is bringing in the internet, your laptops antenna is giving it back out again. Granted, yes, either you or your RV buddy will need to be connected to that wireless adapter, but then the other person is free to be wireless anywhere within 30 feet of the connected laptop (though... with the metal frame of the camper that might be shorted if the other laptop goes outside.)
I'm an outdoor enthusiasts like you. However, I am not so tech savvy. Please look up "How to turn your vista laptop into a router" on google. There are many helpful videos or, if you prefer, written instructions. I have been very happy with my laptops ability to network, though, things get slow once 3 people are using the internet at the same time. Hope this helps!