One thing to think about is to make the tanks sized for 8x10. That way when you do try 8x10 you won't have to build or find new tanks. They make hangers that take 2 5x7 sheets and fit 8x10 tanks. They used to be very cheap but I haven't looked in a while. Used tanks also used to be cheap but maybe that's also changed. If you use the 2 up hangers you can go with 8x10 tanks which should be easier to find. You can also look at the various plastic products in the food storage section of large stores or plastic file folder boxes.