We are planning on expanding our shower to 3'x5' and considering solid surface panels on 2 walls, possibly Swanstone, and not sure about the pan as we will have frameless glass pivot shower door and the third wall will be full glass panel 3' x 7'. Do we need a double threshold pan/base to support the 3rd wall glass panel? It seems 36x60 is not standard in double threshold pans and we don't want to pay for custom. The only one we found is acrylic by Fleurco. Not sure if acrylic is the way we want to go. Jury is still out on acrylic.