I can shed some light onto this as a pilot. But I am not an aerodynamic engineer. Flaps begin by adding more lift than drag. It reaches a null point where the added flap setting adds an equal amount of lift and drag. Beyond that point there is a greatly diminished amount of lift added and the induced drag is rises at a rapid rate.

The civilian aircraft I fly sometimes have TO flap settings of 10-15 degrees. Some are even as high as 20 degrees. I have not seen higher than this. I do know that some heavy aircraft and warbirds have higher TO flap settings. I would be very carefull though. You are flying a model aircraft and not a full scale Hellcat. The median point of added lift versus drag is around 20 degrees +/- 5 degrees for most light plane aircraft flaps.

I also know that many aircraft have been crashed on touch & go by the failure to remove landing flap setting upon adding throttle. With landing flaps set, you add power, the plane pops off the ground early and jumps out of ground effect. Only to mush back to earth nose down. Not a happy ending...

Because most models have unrealistic power to weight ratios you can likely get away with more TO flaps than the model wants. I would also test the setting in the air for severe trim changes before landing or taking off with them. Be realistic in your models power assesment.