I did what you mentioned with half brown rice flour and half tapicoa flour, everything else I followed. (thereislifeafterwheat.com)
The only thing I did was when it was mixing and it was runny, I added a little bit of tapicoa starch each time until it was thicker. (thereislifeafterwheat.com)
And I've also tried using half brown rice flour and half tapicoa with success (I was cleaning out the pantry). (meghantelpner.com)