Factory installed on my motorhome. Circuit is just a panel with a reverse blocking diode. No controller needed because of the small output of the panel (about 0.7 amps maximum).
If you are just using for off-seasonal storage, you don't really need a permanent installation. Just a line from the panel to the batteries, connected with small alligator clips. If you want it for short-term storage between uses, it would probably be worth a roof top installation.
Something like this:
Battery Tender 021-1163 5W Solar Maintainer
Copy & Paste description into google.
You may need more than 5 watts if you total Amp Hour battery capacity is over 150.
2015 T12RBST Flagstaff Hardside
2008 Itasca Meridian 37H