I've found an alternative:

The gang skips the first waterfall by driving off the cliff instead... Indy remembers Ox talking about the three drops back at the camp (we don't have him saying it right before the waterfalls anymore... not sure if it's a problem or not) and he notices this by "One..." and pointing back at the waterfall (and cliff) behind them.

This is what it looks like:

http://fileload.us/1026497336-waterfall_cut2_divx.avi

Yet, this edit is still lacking two things: First I'd like to add the car driving off the cliff in the wide shot of the cliff (after Spalko's closeup) and second, I still need an establishment shot after the second drop. The first thing should be doable, but I have no idea what to do about the second problem.

EDIT: Here's a slightly reworked version. I've tried to fix the mentioned problems through different editing: http://fileload.us/288449025-waterfall_cut2b_divx.avi

Oh, and just for the fun of it: