I went for a drive a couple nights ago with the thin vinyl film over the cooler. It worked better than I remembered. Believe it or not, it was at least 10 degrees warmer.
I like Rick's idea of the foam better. Easy on, easy off. I've got actual fuel cell foam because I make fuel bladders for drones. But what I don't like about it is that it would let too much air in. I think closed cell foam might do the trick even better. Then I'll felt line the perimeter so it doesn't scratch the aluminum too much and may even back it with a foil tape so the hot cooler doesn't melt it.
I'll get a new memory card for the camera, get a manicure and take a few hundred pics, ala patrickt.
More to come...
BTW, I had a fuel psi problem that cut my ride short. I'll post that on another thread.