[onewhippedpuppy]

My aero classes were a long time ago, but I believe the primary purpose of the slotted flap is to promote airflow over both the top and bottom surfaces of the flap. The slotted or fowler flaps would be difficult on an R/C, you'll need some sort of flap track and jackscrew type arrangement as the flaps deflect both downwards and move backwards. Pretty complex. I would go with some sort of plain flap for ease of construction, and just focus on getting the area right. If you just want to go low and slow with short takeoff/landing distances, you could also consider adding leading edge slats.