I did the tile in another bath - house built around 1990. Sub floor is in great shape and level(?). 

Sterling (Kohler) 'Ensemble' unit. It appears there are 8 'feet' that are a part of the 'grid' affixed to the bottom of the unit. Their instructions say to lay the felt pad (IF included) under the unit so that 'feet' rest on it... continue with install. Then use shims to level the tub. When you put the tub into the stud pocket and fix it to the studs, unless you are two inches tall and can climb beneath it, how do I put in shims and know where they are needed? 

Or the next section section of instructions they say to use a mortar base to level it. Lay 1 to 2" mortar under the tub and squish it down to level it etc. 

I'm gonna go out on a limb and assumed the 'feet' are in plane with the bottom edge such that - assuming a flat level surface - there would be no need to shim.

I just got off the phone with Kohler. And I posed the same question about the 'felt pad', and shimming after the fact. They were unable to answer my question Just get a felt pad from one of the box stores...

Anyone have experience with this type of product - molded support grid with 8 tubular feet on the bottom? Will the "felt pad" be sufficient?

[Instructions (PDF)](http://pdf.lowes.com/installationguides/885612241122_install.pdf)