Sweet. Its a surf film. Shooting on red. Majority of film will be edited to music. Quite a few interviews but mainly want to record sounds of waves crashing/ thunder storms/ street noise/ waterfalls and similar sounds.
Okay, that helps. As you are going to be a one man run & gun crew we'll have to approach this differently. That means minimal gear, ease of use, minimal set-up/break-down time.
I must first say that I have no personal experience with the RED camera; here we go...
Everything that I have read from my peers out in the field says "The RED mic pres are
crap!" so you will want a mixer and run it to the audio line inputs of the RED. Now, when you are doing a documentary you are basically doing ENG work. That means two different kinds of interviews; the "man on the street" or field interviews and sit-down interviews. I will make the assumption that you will be running the camera in both instances. For the field interviews you should use a camera-mounted short shotgun. For the sit-down interviews you should use lavs. When shooting the action/nature stuff a stereo shotgun will give you a better sound field. Now, this is a total shot in the dark from me, but based upon my experience, blah, blah, blah what I think you will need and how to set it up.
Start with the PSC DV PROMIX 6. It is a six channel mixer with four outputs. You will need to spend some time dialing things in, but once you have it all set up it should be fairly close to "set it and forget it." You are going to have five sources - one mono shotgun, two lavs, one stereo mic - and by having a separate channel for each one you will have to minimal adjustments in the field once you have gained familiarity with the system.
PSC DV PROMIX 6 Kit - $1,400
Rode NTG-3 Mono Shotgun - $700 (field interviews)
Sanken CSS-5 Stereo Shotgun - $2,100 ("action" shooting)
Lectrosonics 100 Series - Wireless UHF Lav Microphone System (includes Tram TR-50 lavs) - $1,400 x 2 = $2,800 (sit-down interviews)
You'll need cases, cables, headphones, blimp, dead cat and other accessories. Probably one of the more important accessories will be a hot-shoe that will get the shotguns above the camera and away from the fan noise. I went with the complete 100 Series wireless as it doesn't matter if the lav is seen when doing interviews (the B-6 lavs are made for hiding).
Well, that's what I would do. Please, go and get a lot of other opinions.