Sounds like fun!
I'm NOT an aero engineer and I can't remember the last time I stayed at a Holiday Inn, but looking at your application, it is in reality a low-speed situation.
The forces exerted on a surface don't always "scale well" when making models.
I'm guessing you need air movement over both surfaces of your flap to gain the full effect.
That opinion was worth exactly what you paid for it!
Best
Les