Sorry, I have not read all of this thread.
I'm in if you have it, might I suggest East fork lake for the following reasons: Close to home for you (& me ). Easy terrain for those with a recent bad back, but interesting enough to reduce boredom. Water is available, usually. There are some interesting,,, historical areas, well, remains of abandoned (read: Taken by the government) homesteads. A few views of the lake. After maintaining the Backpacker trail for about 7 years, I know shortcuts if need to bail due to whatever reason. Both of the regular campsites (#1 & #2) are less than 1/2 mile from a road so easy enough for evacuation in the unlikely event it's needed. I got back issues also, so I so understand "the best laid plans of mice & men,,,,"
Drawbacks: "Must camp in one of 4 designated back country shelter / camp sites. Water CAN be,,,, "Iffy" at times. regardless of campsite, you can almost always hear the sounds of the highway. Even in dry times, there are often swampy areas to traverse, although in the last 20 years these are becoming less as the surrounding tees mature & thereby draw more water from the surrounding soil.