Elana...YAY for you
I say go for it girl! Go with her and who cares about where the heck you sleep. I say you make a joke out of it, go sleep on the porch...hehehe
Seriously, communication with your g/f would be ideal. You guys need to talk about your personal issues...just lay 'em all out on the table and go from there. You'd be shocked at how smoothly things can run afterwards.
HAVE A GREAT TIME ON THE TRIP and Love Much!!! (Ponder my quote below and remember that)