I always try to stay out of the holding when Im passing a bank angler. I either go to the other side of the river ar get as close to them as possible. If there is enough room I go behind them. I noticed on certain rivers when you groups of anglers, ther is always one dumb a$$ that acts if your boat is not there and proceeds to keep casting. These guy piss me off to no end.
The rule I use when fishing a hole that already has a boat it. I never anchor any closer than I would want someone to anchor to me. This has worked most of the time.