What's the point of leaving it plugged in all the time if you aren't using it to warrant the need to keep it plugged in all the time?? Is it just to keep the batteries charged??
I keep my trailer parked and covered all winter too, but I only plug it in when needed... Even covered, I've used it for an extra room for house guests.. I pull the battery from it and keep it in the garage. Plug it in when needed.
My converter allows for it to be plugged in without a battery, so you'd have to check to make sure yours can do that too..
Anyway, whatever works for you is the way you should do things, but for the last 12 years, I've been disconnecting the battery and I actually still have the original DELCO battery that came with the trailer, but I do use a newer TROJAN for it now, but it's getting to be about 6-7 years old now too....
Oh well, get some new batteries and try a disconnect switch and a trickle charger on them and leave the rest of the rig unplugged.. Or continue with what works for you and be happy!
๐Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.