There's a certain amount of unpredictability in this configuration that no one has mentioned. Imagine the tip loads you will get in a gust... Transferred to the tiny little torque tube holding the tiperon in place! Try using a large hollow torque tube. You know what I mean? Use a lot of supporting structure too. This is probably why they are not used on traditional aircraft.

You will be able to achieve a high angle of attack (with attached flow) due to the geometry of the tiperon... essentially a low aspect ratio wing... at the end of a wing. I mentioned using an end plate before. You may want to try putting an end plate before the tiperon as well. Maybe just a cuff... anything to help keep flow attached to the main part of the wing.

Ken - www.litkoaero.com
R/C Laser Cutting and Design