All: Many thanks for the feedback. We are in the Timmins/Iroquois Falls area - so both very cold, and little/no salt. We don't load/unload from the trailer very often, but rather leave and return to the garage as the main trails are accessible in a few minutes on a small side trail.
We are spray-foaming the garage this week. It's 25 x 40 with an overhead side door for the sleds to enter in-front of the two cars. After insulation, we will be installing a small propane furnace that will be able to get us up to 6-8- degrees C without using too much energy. This will melt all the snow, and I hope the dry climate will deal with the melt water.
Based on all the comments, a conveyor belt would be great I think. Spring time, we should get it outside to completely dry both the concrete and the rubber.
Thanks.