I would check with Thermarest before applying the silicon/mineral spirits mix. The mix is pretty well tested for use on silicon nylon but I have never heard anything about using it on the air-tight fabric used with Thermarest pads.

I am having a bit of a slick floor problem with my new Big Agnes Fly Creek. The floor looks a lot like silnylon but BA in an email to me recommended using McNett's Seam Grip for non-skid spots; not the silicon/mineral spirits mix.
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May I walk in beauty.