I would plan a short camp with your friends and invite him to come along, but don't pressure him. If he chooses to not go, you go ahead with your friends and enjoy yourself. Take plenty of pictures and tell him all the fun you had when you get back. Maybe he will change his mind if he feels like he's missing out. If not, it's alright for couples to "do their own thing" once in a while. I wouldn't give up something you love just because your husband doesn't enjoy it.