Yes, I would need all 4. Permanently bolted would be fine I think. I can add some a thin rubber around the pinch to avoid vibration while driving. I could just use a block of pine or maybe something even harder instead of their urethane blocks, but I figure that might eventually bend the pinch weld so some sort of pads seems like the better option.
I know it would work, but I am uncertain about long term use since I intend on using the Quickjack to get the car up and do a days worth of work (no stands, yes the Quickjack is safe). I am not sure if it is a good idea to support the car that long on the horizontal sheet metal on either side of the pinch like your pads do. I am under the impression that you never intended on using the pads for long periods of time, more as an easy way to get a side up and change tires/etc. Thanks for the help/advice!
I know it would work, but I am uncertain about long term use since I intend on using the Quickjack to get the car up and do a days worth of work (no stands, yes the Quickjack is safe). I am not sure if it is a good idea to support the car that long on the horizontal sheet metal on either side of the pinch like your pads do. I am under the impression that you never intended on using the pads for long periods of time, more as an easy way to get a side up and change tires/etc. Thanks for the help/advice!