This sounds like some mess is about to brew before too long with all this camping, cooking and over nighting.
Actually, not necessarily. My husband's best friend is gay. They used to spend up to a week at a time sailing on the Chesapeake Bay. This guy was gay, but he was staying waaayyyy in the closet, because his parents (devout Catholics) are still alive.
It was one of those don't-ask-don't-tell situations. Hey, if the bf's family wanted to be in denial of the obvious, fine with me. As for my husband; TOTALLY heterosexual.
I asked my gay cousin about this situation. He told me he has a number of straight men as friends, and it is nothing more. He loves them like brothers, but he isn't going to hit on them; it would be an offense to him and his friends.
Your husband's gay friend may just really like him. A crush? Possible, but not probable. If your husband isn't doing anything weird, I wouldn't worry.
Like I said, my husband lived in close quarters on a sailboat with his best friend. NOTHING ever happened. Do I have any doubts? Nope. Hubs was/is a drunk, but he doesn't swing both ways.