Though you're unlikely to experience freezing conditions, I think the better approach is to make sure the whole assembly can drain - ie drill a drain hole through the base into the stanchion tube as low as possible, esp now that they're off the boat.
Years ago we bought a California boat, the first winter freeze we had split one of the A frames on the wheel support... unbeknownst to us it was full of water, had no way to drain until it froze, split, and thawed again.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"