I wouldn't go under 8ft in length but that's just me. I subscribe to
@pcray1231's idea of as much length as you can get away with. IMO, once you go under that length you lose a lot of line manipulation abilities and the trade-off of being able to cast in more confined spaces doesn't really pay off. It's impossible to cast through those rhododendron canopies, though a shorter rod would help working around those kind of hazards. People often forget that even short rods require room to cast unless one is roll-casting, dapping, or bow and arrow style casting. There are very extenuating circumstances where I would employ a 6'6" rod, actually only one creek I can think of where I would use a rod of that length, and on that creek I doubt using 8' rod vs say a 6'6" rod would make much of a difference, though I use the 6'6" rod to justify buying it.
My rod for the creek you are fishing would be my Winston 4wt 8'3" for indicator nymph fishing and my dry or dry/dropper rod would be my SAGE Little ONE 1wt 8'2".