Kohler Levity Tub Door Installation

[Arch1]

I bought a new sliding tub door (Kohler Levity) a couple of months ago and am ready to install it. NOW I see it requires a 3" wide tub flat. All 4 tubs we have in 2 properties have 2-1/2" flats. Kohler says not to install it because the base supports the whole thing. I agree, but the base will be on a solid flat surface, side rails attached to walls (5 screws each side), and top rail attached to side rails. The only issue I can envision is the center guide will overhang the inner lip about 3/8". Anyone have any experience with this or similar, or have suggestions? We are stuck with the door (past return date policy of the seller).

 

[Tuttles Revenge]

The specifications clearly show the base being exactly 3"wide where it contacts the tub flat surface. I can't envision the difference impacting performance, the entire weight is born on the walls and the cross beam, but it will be an aesthetic thing.

https://www.us.kohler.com/webassets/kpna/catalog/pdf/en/K-706001-L_spec_US-CA_Kohler_en.pdf