I use Bio Kleen and have installed a valve where the drain plug was. The cross member for the front jacks is just in front protecting the valve the valve handle is on top of the pipe to prevent snagging road debris. One pipe nipple, one 90, another nipple and a ball valve with a barb connector. I installed a short pc of hose with a plug to assure a seal if the handle gets bumped.
On the fence where I park I mounted a racor215 water separator which then goes to a 10 micron then 2 micron filter. Then the fuel runs through a fuel pump and is returned to the tank. The tank access is a hole in a fuel cap with the hose passing through it. I sealed the hose to the cap to keep it waterproof. I run this setup whenever we are home and parked.
I used to have an algae and water issue.........no more!