I HIGHLY agree with 'popeyez7' on the no rollers thing! I made 18-inch-long padded/carpeted hull cradles from the same piece of scrap sewer pvc tube that's the storage tube.

Strip the boat of EVERYTHING. Down to just fiberglass hulls and crossbars (remove any barberhauler cleats screwed to crossbars). Cover any remaining exposed cleats (downhaul riveted to mast) with Hefty lawn and leaf bag, but poke holes in the bottom of the bag to allow for drainage. Drive the trailer tire over Hefty lawn and leaf bags, pull them up and over and tie them off to protect the tires from UV wear. Unplug the drain plugs and tape over the holes with nylon screen door meshing (cheap at Lowes). You WANT airflow through the hulls to allow for condensation to not build up, but don't let mice use your hulls as a winter hibernation home. Mice can easily fit through your drain holes and a cat hull is PERFECT for building a nest. NO tarps! It'll only catch rain/snow and weigh down and a polytarp the rubs on the hulls from a little wind will wear off and stain the hulls.

Just remember that fiberglass and aluminum with airflow is fairly impervious to weather/cold. It may get a little dirty, but is easily cleaned off in the Spring.