However the question you did not ask, but I will answer in any event is what type of film to use? IMO use a color negative film. Slide film has traditionally been a favorite of pro's, but the exposure latitude makes it very unforgiving. For the benifits of slightly better grain, IMO it's just not worth the sure to be disappointing results of slide film when improperly shot. Your camera setup is just not ideal for fine tuning exposure.
The type of film I would recommend is fujicolor press 400. Why? Fine grain structure for a 400 speed film, wide dynamic range, wide exposure latitude, and it does well under difficult lighting and mixed light situations. This is a professional film. While they may sell it cold, it can take some punishment, but I'd keep it cool if possible until maybe the evening before you shoot it. If you want to use this film, don't expect to find it at your local Safeway, you will likely need to find a camera store, and film is becoming more difficult to get ahold of, so don't just show up at a local camera shop with the expectation of getting a dozen rolls without calling first.
I'm recommending this blind from a shooting UW perspective, even if I have extensive experience with film. This would appear to be the best choice, but if others that have used this film have other reasons to use something else, I'd potentially take that advice. OTOH, negative film is all C41 process, and I can think of no reason that this would not be a solid choice for any shooting situation.
For 100 speed film I'd recommend Fuji Superia.
You may want to choose to use a 200 speed film at the 100 speed setting. The end result would be 1 stop of overexposure assuming that there was enough light to gain the extra stop. Overexposing negative film generally results in more saturation, and good results. It should NOT wash out. Negative film has an exposure latitude that allows up to FIVE stops of overexposure (not that I'd recommend that).
I would NOT recommend overexposing a positive or slide based film. In fact I'd strongly recommend against that as overexposure in slide film is a great way to generate very bad results. You could try some slide film at ISO 100. Underexposure of slide film by about 1 stop is generally not too bad. In fact Kodachrome like to be underexposed, but not necessarily by a stop, more like 1/3.
Good Luck, and enjoy the trip.
