We have a 1993, 22" pontoon that we dock at a state park. We keep two, 12 gal. portable Moeller fuel tanks on the back deck, secured by heavy black rubber bungees, with the s-hooks crimped around the fittings so they can't come loose. If the tanks have any amount of fuel in them, they're difficult to remove, but someone stole a full tank in the past week 
My question is, what are the reasonable (expense and effort) options to prevent this from happening again? Obviously, the best way is to transport them back and forth with us, but that's a pain, especially having to drive 45 minutes to get to our dock. I was thinking, securing them with locked chains, and locking gas caps. They could still use bolt cutters or poke a hole to empty the fuel, but at least it might make it more work than it's worth, and the potential thief would move on?
Any suggestions are appreciated!
My question is, what are the reasonable (expense and effort) options to prevent this from happening again? Obviously, the best way is to transport them back and forth with us, but that's a pain, especially having to drive 45 minutes to get to our dock. I was thinking, securing them with locked chains, and locking gas caps. They could still use bolt cutters or poke a hole to empty the fuel, but at least it might make it more work than it's worth, and the potential thief would move on?
Any suggestions are appreciated!