As I've mentioned before, I had ischial flap surgery on January 7th and I am looking forward to driving again in a few weeks. I want to get a gel cushion/pad for my car seat but I'm having a hard time finding one with the right measurements to fit in the base of the seat to prevent slidding of the cushion. The BACK of the seat base on the inside of the high lipped contour of the outer edge of the seat is 12in, the FRONT of the seat base on the inside contoured lip edge is 15 inches and the total seat base LENGTH is 19 inches. The TOP part of the contoured edge of the seat to the bottom part of the seat is 2 1/4 inches deep. I would like the cushion to be about 2 inches thick so that it makes for a smooth transition over the edge (lip) of the seat from my chair. I am most terrified of the transfers to the car since there is about a 20 inch gap to transfer over between my chair cushion over to the seat of the car. Does anyone know where I can get a cushion for the car made with the exact measurements I need?