I think I would try and build a raft, or better yet, a good boat, out of downed trees, etc. By the time I got it anywhere near finished, the river would have subsided to the point where I could safely walk across. Either that, or someone would have arrived on scene with resources (like a helicopter) that would offer some other, more feasible alternatives. Scouting up or down stream might offer some surprising options (although I realize you have ruled that out)

Real world situation, you get yourself comfortable and wait for better conditions. Been there, done that, and I have dealt with the consequences of the actions of those who, for whatever reason, felt they had to cross the river right away (one of these, evidently, was a gentleman who was missing the Super Bowl; we'll never know for sure because he drowned immediately).

There are few situations more deadly than dealing with flooded, rapidly running waterways. Patience, grasshopper; wait for better times.

By the way, even if I built my hypothetical raft to cross your hypothetical river, there is still a good chance I would drown my hypothetical @$$ in trying to cross.