I've found that using a majority of tapioca in the blend gives the best results as far as texture and crisp, it's one of the best flour substitutes I've found. I think the last one I made was about 70% tapioca, 15% oat, and 15% brown rice. I pre-bake the crust on a stainless sheet for a good 6-7 minutes so that I can then transfer it safely to a peel and get it loaded up and onto the stone, and by the time the toppings and cheese are done the crust is nice and crispy without being gummy on the top or inside.