On our '85 Westy w/ AC, we went one step further after the water started flowing down from the rear deck.  We replaced the dry kinked drain hoses with flexible silicone tubing and after discovering that the tray is lower than the outlet tubes, we re-routed the tubes and lined the compartment with rubber membrane to catch any over accumulation.  I have photos of the project if interested.
                                Dave Creasy
'78 Westy
'85 Westy
'93 EVMV 5 sp.