Number one thing you have to do is seal off the edges and floor around the roll -up garage doors. You need to get garage door floor and wall seals off Amazon. They go on the outside wall up against the flashing on the side and top. The floor ones are extra squishy and the door settles down on them eliminating any airflow under the door.
All of these are critical to creating a maintaining an environment that won't mess up your rails and cloth.
I use a 7ft valley with Ridgeback Pro rails because I'm in Texas and even with all theae seals and a ductless AC/heat unit it's still not an environment a solid wood table would do well in