Switch to EDF, then you can do it.....although there may not be a need to....

It would have to be an engineered system to fit a specific application..it is not just a matter of throwing clam shell doors in the exhaust stream.....you have to consider what is going to happen to the deflected exhaust..is it going to recirculate back into the intakes and cause a compressor stall (F-35), will it impinge on the model's structure and start to melt stuff (My son flies a full scale and they can't use reverse thrust below 40 knots as the carbon fiber stuff and cabin windows start melting...what about debris and fod that are kicked up? will the added back pressure cause blowback into the fuselage? (that would be interesting in a non bypass system...) Lots to think about......