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.
1984 Fast/Nicholson 345 "FastForward"
".. 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)