We install an inexpensive solar powered battery tender / maintainer on our gooseneck trailer so that hopefully we won't need to replace the battery every year.

10 Watt 12 Volt Solar Panel Battery Charger: https://amzn.to/3i5xhrS
Rubber Grommet Firewall Hole Plug Assortment Kit: https://amzn.to/3i2tf3z