"Cook",

Yes, I used my Thermarest Lite over the RidgeRest once and it worked OK but not quite as well as the regular thickness 3/4 length Thermarest.I have to add that with this 3/4 length mattress I use a closed cell foam 18" sit pad under my lower legs as well.

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