I store my bike (E150RS) upright with a hook system for the front wheel. This places the down tube at the perfect angle for the battery to just slide out and is also really easy to put back in as everything is at waist height. The screw idea is a great hack - cheers!
Fitted the rear one recently to my 150 RS and am very pleased with it, the fit is really good and as others have mentioned no clogging on muddy rides. Can also recommend the mudhugger front that bolts directly to the fork arch.