Thanks for all the input and PMs folks!
Talked to the rep at Johnson's Plastics in Edmonton and they can get me a 4x10x1/4" sheet. $275 per sheet.
From the research that I have done, UHMW is more resistant to impacts in cold weather. Can use HDPE for flaps, dividers, risers etc to keep the cost down as well.
I am picturing a sled somewhere between the two designs in the following links.
https://www.airframesalaska.com/6-Si...k-p/nswsp6.htm
https://www.yukonsleds.com/
MS