I leave our TT plugged in year round.
I've used Schumacher brand battery maintainers on all my other items that need off-season battery tending. Used on snowmobiles, boats, motorcycles, cars and even my old Cessna 172 airplane with a 12 Volt electrical system.
2020 Jayco JayFlight SLX 175RD
2016 Toyota Tundra XSP-X 4X4
Redarc Tow Pro Elite brake controller
Fastway E2 Trunnion WDH