On many Monaco coaches, there is a fixed panel on the curb side directly opposite from the road side wet bay compartment door. If you look closely, one side of this panel is hinged similarly to all of the compartment doors, and the opposite side is held closed by some tabs, screws, angle brackets, or some combination of them. If you can remove the screws or bend the tabs holding the panel in place, you can usually swing it open like any other compartment. This will usually give you a great view of the tanks and many of the connections. This should make it much easier to find the source of the drip, and hopefully will give you sufficient access to repair it.
Adam and Sue, and a pack of little furballs
2007 Holiday Rambler Endeavor 40PDQ Limited Edition - Cummins ISL 400
2013 Ford F-150 FX4 toad - USGear Unified Tow Brake, Roadmaster Blackhawk II Tow bar, Blue Ox baseplate
Home base near Buffalo NY, often on the road to a dog show