Smashed lwr units and props can happen, I run with a custom built cage around my prop, I loose about 10 hp but I can sustain decent impacts. The river is high volume tho, low water levels you need to worry about rocks, the high water levels not so much an issue. Theres a classic whitewater inflatable race video out there
This type of river will smash your lower ends. I was hoping this kind of race circuit or scene still existed............
Once you learn how to read a river you can figure out where most of the deep water is. Its just a question of staying there. I have also found most of the other rocks by now.........If you ever want to come up for a cruise in my boat by all means let me know, I can show you a whole new world of inflatable boating.
As far as jets, they would work great, even better if they were on inflatables. I dont think you want to be running a boat in the rapids tho any bigger then 18 feet.