I have the same boat as you. I talked to a guy who sells chargers and he recommended a dry mount charger. He claimed that for use with shore power and running 12v appliances, it was a better and more durable solution and it runs cooler. I went with the (now discontinued) Pro Mariner 1240i 40a 3 bank charger and moved the location to inside my battery compartment. The original location would probably have been fine though; if you have water that high, your battery charger is the least of your worries. Bolted it through the fish box, which I only use for storage. Had to remove the insulation from the backside of the fish box to mount it. Doesn't interfere with battery removal or maintenance. We overnight with shore power at least 2-3 times a month and so far, so good, although only about 16 months. If you want to talk to the guy, he's on THT as chargerguy and also on ebay as chargerguysales.
