All great advice gentlemen. Lots of good tips here that I won’t be able to rehash as well as what’s already been done, but I’d also look into doing some re-con work of the area.
Reservoirs are alot of fun because of the variability, but depending on when they were flooded, many times aerial photography exists, giving you an incredible advantage even if there’s no way to orthorectify (line-up) these maps with known locations. Simply knowing that road-beds, old meanders in the river channel, etc. exist offers you a reason to go out there and find them. They’ll also help you find the most mature and well developed timber, as well as points/turns in the timber to focus on.
As for where to fish, if you’ve got good flow in that system, first/foremost be careful. The main river channel area is always dangerous. Also, don’t be afraid of the depths in such a system, esp. mid-day. Low-light feeding times will bring them out of the river channels and their edges, and hopefully your scouting work will have found a natural pathway or corridor up to these shallower feeding areas.
As another poster pointed out, make sure to have your holes drilled so you can follow the movements of the fish as the morning/night progresses. They’ll still be feeding often, esp. at first ice, but you might have to give chase.
Good luck!
Joel