I've made several big, full width Xs of silicone dots right from a caulking tube on my old full length UL Thermarest. I did it B/C I have a Contrail W/ a slippery silnylon floor. Works well. I'm sure the urethane SEAMGRIP would work too and may cost less.

Eric
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"There are no comfortable backpacks. Some are just less uncomfortable than others."