Hey Mark,
I just converted 3 hrs of XDcam 1080i at 60 fps. to Mpeg2 for SD DVD authoring. To convert 1.5hrs. it took my intel 3.2 mac pro 4.5-5hrs.
Just running some data numbers… If you shoot one hour of usable footage a day your going to need 1TB drives to get through 6 weeks. These numbers are very close for both DV25 or HDV 1080i formats.
I agree with Michael… The EX1 or EX3 is an excellent choice.
It sounds like an awesome adventure. Best of Luck!