If you upgrade the trailer battery to a deep cycle RV or marine style battery, you'll have enough battery capacity to use a DC to DC battery charger (most hobby shops sell them to the RC crowd) to charge your glider when it's cloudy. Also to run one or two LED floods mounted to the underside of the trailer clam shell for work lights and after dark rigging etc. Trailer battery can jump start cars, run an inverter, and more.

bumper