kohler tub and shower module question

I am installing a Kohler Terracina tub and shower module. The unit has a lip on the bottom front edge which hangs below the bottom of the tub area by approximately 1.5". The install instructions make no mention of supporting the unit from underneath. Is this lip supposed to support all the weight of the tub, along with the nailed flanges, while the base hangs in mid-air?
Thanks

Check the installation instructions carefully. IF this is an acrylic or fibreglas unit, it is likely you should support it in a bed of gypcrete or structolite.

Jimbo,
thanks for your help. Are gypcrete or structolite liquids.

They are more of a slurry. You can also use drypack mortar - a mix of 5:1 sand and portland cement (mostly sand).