I have coverking seat covers from costco, like them fine, but still feel a bit 'sinking' into the seat, I would like some kind of seat cushion to sit on to be just a little higher up, any suggestions for a mat/pad, if you know of or own a nice one (something that will not slide around), thanks for the tip or link.
'

 

I think part of the sinking (at least on my truck) is that the foam has formed cuts where it meets the seat frame (the wire mesh section). I was thinking about putting something between the foam and the seat frame to keep the foam from sinking into the seat frame but have not done anything yet. I am not sure what would be strong enough, it would have to be something like plywood or 1/8th inch sheet metal.

I will probably do nothing and get some comfortable seats from a newer car.