Been at seasonal site for 7 years. In spring, the slide goes out and stays out (until fall). In fall, the slide goes in and stays in - for winter storage months. When slide is in our out, I also discovered that spray foam within its lower corners help keep mice out as well. Thus, I spray foam $1 worth of foam in spring and $1 worth of foam in the fall. This works great for our seasonal site.
If you are DIY person, one might want to create a sectional hard top for their slide as well. Connect to trailer using "sloppy bolt" hinges and support its outer edge with telescopic steel posts. Thus, adding a slopped hard cover to your seasonal site TT. And, make the sectional panels to be removable by using a sloppy hinge pin. During year 3 at our seasonal site, I build my slide's hard cover (3.5 ft by 4 ft overlapping sections). It works great!! Especially during hard rain storms. re: - click here -