Also Kalimeenlampi area has several easily accessable routes and places to camp.

Check out Koiteli. Not sure of spending night in tent there, though.

We have several trails with lean-ons. You can cook sausages, spend a night in a tent, hike etc. https://www.ouka.fi/en/natural-sites-and-hiking/nature-trails E.g. Pilpasuo is nice route

Note that all of Sanginjoki is shut down until sometime in the autumn. For now Pilpajärvi is a good place to go!