Fallstorm, returning to the Bike Friday possibility, this might not be a choice right now, as you mentioned "college finances", and not being able to buy the bike until a week before the trip. Bike Fridays are fairly expensive, and if you get a custom built one, you're probably talking at least a month lead time.
But for future consideration, they can build bikes for heavier riders, although I don't know if they have an upper limit. Besides a reinforced frame, you're probably also looking at stronger wheels, with more spokes than usual. Also, you could look at their travel trailer system, where the suitcase that carries the bike turns into a trailer that you can tow, carrying your stuff that way instead of using panniers. That reduces the weight the bike itself has to carry. It might also make a difference whether you're talking about a 275 lb rider towing 75 lb of luggage or a 300 lb rider towing 50 lbs.