Welcome to our forum.
First off, congrats on one of the nicest tubs available! This machine has everything and I wish you and your family many years of enjoyment with it. Did I mention the Flames still suck! anyway...Every platform is level or close to. The base of your new tub is pressure treated 2X4 and it designed to prevent rot like any quality decking material. An added base would be somewhat redundant.What color did you go with?Steve