Take the seat off and stow it locked in the truck. Then I'd by me one of these locks for it being sure to put it through the hull somehow (look for drainage plug) https://www.amazon.com/INTEKIN-Bicycle-Security-Mounting-Motorcycle/dp/B08P6MB5JB/ref=sr_1_25?crid=2HVNNQFLM151R&keywords=noise+lock&qid=1644203026&sprefix=noise+lock%2Caps%2C74&sr=8-25