I have plenty of homophobes in my family, so I understand what you're feeling. My best advice is to not let it get the best of you. Don't let their narrow-mindnedness bring down your confidence and composure around them. Don't let it be the elephant in the room. You being gay is just one small part of what defines you of being an individual person, and it's something you should have pride in. There's nothing that needs to or doesn't need to be talked about. You're gay, it's as simple as that. Don't bring it up. If they do, don't let any tension build up or let any arguments spark. Just say, "yeah, I'm gay. So what? If you don't like it, don't talk about it." And be respectful of their views on it, no matter how mind-boggling it can be to you that they feel that way. I hope your trip goes well!