It is possible to improve a wings lift by adjusting the camber with flaps but setting it up to do that is going to depend on your radio system. If your radio only has a flaps up/down switch then it's not going to work as well as it would if it had a "Dial" control that allows you to use only partial throws and hold them in that position.

This doesn't only work for thermal planes. Years ago I modified a 2 meter poly bird that I flew on a slope to include flaps. I could face the plane away from the slope at the crest of the lifting "wave". drop the flaps and actually hover in place with no control imputs from me at all. Turned out to be a handy thing to be able to do when I wanted to take a break and stretch for a minute or two.

My latest modification was to a 99 inch Windfree that I built from a 25 year old kit. I swapped out the thin spruce spar stock for solid carbon and added a sub-spar that ran the full length of the wings. I attached flaperons to the sub-spar and controlled then with Hi-Tec M125MG servos which barely fit into those thin wings. The difference in flying this version versus a stock Windfree is nothing short of amazing. Going from rudder/elevator only to having the additional controls in the wings improved the flight characteristics 110%. It will thermal tighter and can use lighter lift than it could before. Plus it looks pretty cool to me as well.

Another thing to consider is to make it so your flaps can be reflexed upwards a bit. This will give you faster speeds when flying through sink while you're moving from one thermal to another. Reflexing the flaps acts to extend the airfoil. Needless to say the less time you spend in the sinking air the better.

The only silly question is the one you DIDN'T ask.

Jeff