Canoe and Limited Resources Fishing/Camping Trip
There's also island camping on Caldron Falls and High Falls but you'd have to potentially deal with a lot more boat traffic on both of those.
To get the 3-5 days of camping you're looking for you might have to do more than 2 flowages or take your time going down them. I think from boat landing 14 to the Johnson Falls dam it's about a 2 hour paddle if you're just paddling and not stopping for anything. From the Johnson Falls dam to Kirby Lake Lane I believe it was about 3 1/2 hours of paddling. Sandstone has a pretty swift current on the upper end so even though it was only 1 1/2 hours longer I think you cover a lot more water in that time. Last time we kayaked this stretch we saw a sow bear with her two cubs at the waters edge. Scared the crap out of us because we didn't see them at first until the took off and started crashing though the brush!
Link to the Peshtigo River State Forest below. http://dnr.wi.gov/topic/StateForests/peshtigoRiver/documents/PeshtigoCamping.pdf
The other option would be one of Wisconsin's many fine rivers. The best part about river trips is the river does the work for you if you pick the right one. Load up your canoe with as much stuff as you can safely hold and the river will take you. The Flambeau River State forest comes to mind. The Pine and Popple river systems or the Peshtigo could be good options too. Look at a map, make a float plan and live on a river for five days. Heaven.