In my experience, UHMW as used on airplane skis, dog sled runners, etc won't hold wax for very long--about one landing, actually, depending on the conditions.
The Rosti Fernandez retractable skis use UHMW that is prepared like the bottoms on downhill skis, and those skis WILL hold wax for a bit longer, and it really does help on those skis.
But, most skis have a really slick bottom material, and the wax just scrapes off really fast. Besides, have you ever tried waxing a set of skis that's mounted on an airplane??

Good luck. I tried, but...
Warm snow (as in temps of 40 degrees

) is ugly stuff. I would NOT land in snow on skis if the prevailing OAT was over about 30 degrees. Now, there may be situations where that will work, as in shallow snow, big wind, etc, etc. But in general, if the temperature is that warm, you ARE going to use a LOT of room to takeoff.
IF you actually take off, that is. I've waited till 3 AM more than once in spring snow conditions, with deep snow.
Ski flying is a major learning program. Just make sure you've got good survival gear with you and you'll be safe camping out, cause sooner or later......you will.
MTV