I'd use a cactus mix for better drainage, or you can mix your own. ( 1/3 compost, 1/3 perlite, 1/3 sand )Frost will kill them and turn them into mush...I'd bring them inside the trailer if there is frost danger. You could build a small hoop house and have them protected when over wintering.
Good job in putting those fern cuttings in pots! Thanks for sharing!