Re: fall fishing
I have a propane shower from Bass Pro, that I carry in my car with my tent. I use it at Elkmont or Cades Cove. It has a battery powered pump, propane canister heating coil. You can heat water out of a stream/ lake very quickly. I bought it for N. F. campgrounds out west, cost about $100 but have used it years. Too big to back pack though.
I don't think backpacking in is that much of an advantage in the Park, if your goal is only to just fish. I enjoy doing both- backcountry camping and fishing. If I want to just fish, I found I travel faster with just my fishing gear.
I think there is a difference between camping in a bear closed area and fishing in one. A bear might be in a high country campground might be at Elkmont the next night. If there is a problem bear in an area I want to fish, I make sure NOT to have any food around and run my Day pack, etc up between some trees. I ,also, carry a canister of bear spray on my belt. I have NEVER FELT THREATENED THAT I have had to take it out, even with a bear is present. The park is saturated with bears and they travel long distances. 95% of the time NO FOOD- NO PROBLEM.
My son guides hikers in the Adirondacks. In July, his group camped near a trail shelter, with a fenced in front, that was already filled. That night they heard screams, yelling etc. as a bear came through the door of the shelter to get at the food the other group failed to run up lines. He and his groups had hiked for 8 weeks in that same area and only saw glimpses of two bears while following bear- food rules.