Keeping the sleeping pad from sliding

You might want to take a look at the following article by Jim Woods:

A Treatment for Silnylon Floors

It sounds like you’ve already done something similiar, but maybe there’s something there that will be of help.

Thanks Ernie. I read that well written article and then I went and repainted the entire floor. Amazing how much of the silicone slurry it soaked up and I think that will take care of the problem, plus it increases the durability of the silnylon.

Try flipping the pad over as well. I believe the top of the Prolite pads have better traction than the bottoms.

Try putting your pad inside your sleeping bag.

I have a short Thermarest Prolite 4 and have also experienced the problem of the pad sliding around on the silnylon floor of my SMD Lunar Solo e (same thing with my old original full-length pad).
Although treating the tent floor is an option, I prefer to treat the bottom of the pad so it will stay put. The "slipperyness" of the floor is otherwise not an issue as long as the pad will not move around. Also, treating small areas of the pad will be much simpler and weigh much less than treating the larger tent floor.
Not finding any definitive answers here or elsewhere, I emailed cascadedesigns.com and, along with additional observations, posed this question:

"Can you recommend a treatment that will prevent slipping on silnylon, not be too tacky against other items such as clothing, and adhere to the pad surface permanently?"

The answer I received (very promptly, by the way) from customer service was:

"The best solution is to pickup some Seam Grip, a urethane seam sealer, from a local outfitter and place small dots of it on the bottom of the pad itself. This will help provide some friction for the pad to the tent floor without making the pad sticky."

Note they recommend a urethane-based sealer, not silicone. Hope this will help others.

I also have the Tarptent Contrail. One night after hiking to dark with nothing close to a level area. I pitched the Contrail perpendicular to the incline and used my other trekking pole on the outside of the tarptent about midway to prevent me from sliding. I did pitch the Contrail the other way and I slide to the bottom. I also did as the instruction suggested. I don't think anything could have helped the situation though.

If you're listing to the side, you can try a tree limb under the tent floor alongside of your pad as kind of a railing to keep the pad in place. I've used a few rocks, too. If the angle is great enough, nothing is going to work perfectly. Sometimes all you can do is go for the 'best fix'.

I think that if the pad slid around on level ground, the problem may be with your sleeping style rather than the pad. I have used my theremarests on many surfaces, including silnylong, PU nylon, 3 mil plastic, Wal-mart tarp material, tile, wood floors, etc….and have never ever had a problem with one sliding around.

Coating the floor of your tent with anything will add anywhere from 4 oz to an entire half pound or more of weight.

As long as you seek out level ground(and yes, you can ALWAYS find it), coating the bottom of your pad is a complete waste of time and weight.

Same goes with the seam sealing—unnecessary weight for minimal benefits.