I went out and bought one of those 3/4" thick horse mats. I found it a local farm supply store. It was 4' x 6' x 3/4" and it was around $50. Oh, and insanely heavy! I cut three strips off of it, each 8" wide. One for each pontoon. I then trimmed 3" off the length of each so that whoever sets the mats for me can easily figure out the spacing even if I'm drifting around off shore. By making an H shape out of the three mats, the two outer ones are perfectly spaced for my outside toons to be centered on each one. For the center one, they can fold the sideways mat in half and make a mark, then lay it down so they are all parallel. I think it will work great and they will store easily in the center storage. Thanks for the tip @oldrem3! I'm going to try it out on sandstone this weekend. Here are some shots from my driveway testing after chopping up the mats. The H formation to set the width of the outer mats: Now ready to beach: Very thick and strong rubber. Not very fun to cut. I may still drill holes in it to reduce overall weight and help it sink faster.