There aren't many places outside of California where folks drive an old convertible year-round. In the south, they're often stored through the summer when it's too hot, and here in Minnesota they're put away in the winter when it's too cold. Or just as often, when the streets are too salty.
The TR6 has a pretty great heater, and i've happily driven it in 30F degree weather with the top up and heater on, comfortable and warm though a bit more cramped than if the windows were down. Still, it would be terrible on the snow, and it's not worth the risk to drive when there's any amount of salt to encourage rust.
I live in the city, so storage space is at a premium. I admit getting envious of club members who live in the country and have a second 2-car garage just for their old car projects. Long ago, before i had a second car, building a 1.5 car garage seemed like a good compromise to gain some shop space while retaining some of my small back yard.
Happily, we have a small daily driver, so with a bit of shop tool reconfiguring for the winter, i can put the TR6 on casters and push it sideways, with enough space to park the daily car inside and avoid scraping windows for 4 months of the year.
Winter prep means one last drive to thoroughly warm up and dry the engine and exhaust, a full tank of gas with stabilizer, and some basic critter-proofing. I should change the oil, but that engine needs a rebuild anyway, so i'm not doing it this year. I shut off the fuel valve (installed just before the filter) and disconnect the battery, and that's about it.
A car cover keeps it mostly clean, a tarp and cardboard underneath to catch any oil drips and keep condensation down, and some cardboard along the side to protect against opening doors next to it. Put away for the year, or until i find someone to rebuild that engine over the winter.