Seat Foam Modification or Shaving - Anyone Had Success With This?

I've called a few auto upholsters who all say they do seat foam shaving / mods, so I'm wondering if anyone has done this either at home or at an upholstery shop and how it turned out.

I'll be looking at having my used Prius seat bottom foam thinned and widened to sit lower in the car and have room to sit between side bolsters, not on top of them.

 

Yeah, 'twas Toyota's intention to have those raised sides hug thighs, but for me, they just press into them. Notice how the 2010's flat portion has been widened out as it ought to have been all along.

I pay more attention to Honda's seats and steering wheel / adjustments as a better benchmark for a small car. A Civic's seating blows the Gen2 Prius' back to Japan.

I see no other alternative to get my body down a little lower to floorboard. Cannot recline seatback any more as reach to wheel is max I can tolerate.

I looked at dogfriend's mod to lower seat height about an inch, but I don't want to cut the side frame support brackets.

 

I would need some kind of large caliper to measure how thick the foam is in middle of seat bottom area. From pressing on top / bottom of foam, I'll bet it's pretty close to 2" thick there.

A bit of trivia - I was quoted $185 to $190 + tax from Toyota for that seat bottom foam only. Ouch.

 

Basic measurement shows the seat bottom foam to be ~ 3" thick in the flat portion. But, the surface of foam cushion (on bottom of seat) has a felt-like texture which I'll bet is for some kind of protection (against dust mites, etc?). So, any shaving of the foam would ruin that texture.

I might talk to an auto upholsterer to see what the possibilities are. Anything done would be on my used seat.

My original seat sits in the house and shall not be modified.