I last used my tailgate carrier last year just before Christmas. I drove from Newcastle to Swansea with 2 bikes on the back in atrocious weather.
I got back late in the rain and quickly took the bikes off and dumped them in our basement. Then promptly forgot about them till the spring.
When I came to use the bike again, they were in a horrible condition. One had completely rusted..... chain, spokes, steel screws and nuts etc.. Completely spoiled the bike which was a relatively new acquisition.
So this is a word of warning that low slung tailgate carriers will collect all the muck off the roads, including salt at winter. So be sure to give your bikes a pressure wash soon after.
John