Until I read your post, I didn't realize that there were RV generators that you could set to run on schedule. Nonetheless, I don't think it's a good idea to do this unattended in a storage yard and I would think that the storage yard owner wouldn't be happy with you doing so. There's too much risk of a fire if something goes awry and it's not just your rig that would be at risk. It's certainly not something I would do.
Here's a link with some good info on exercising your generator:
Your MH needs exercising as well so you might want to drive around at least part of the time your generator is running since idling isn't enough for your MH.
Rather than disconnecting your batteries, I'd install a simple battery disconnect switch. I'm not familiar with your rig but you may already have a switch for your house batteries.