not knowing the climate you live in its hard to say but i would suggest trying to locate old pallets from a shipping yard like a brick or lumber is shipped on double stack them keep stuff up off ground and cove with a tarp and tie it down if you are near a marina there is a shrink wrap that can be applied over the tarp to secure it even better most marina have it where else to find it i dont know
not knowing the climate you live in its hard to say but i would suggest trying to locate old pallets from a shipping yard like a brick or lumber is shipped on double stack them keep stuff up off ground and cove with a tarp and tie it down if you are near a marina there is a shrink wrap that can be applied over the tarp to secure it even better most marina have it where else to find it i dont know