Time came to fix my own leaking grey water valve. Taking John HD's lead, I decided to make a real access panel so I could get to the dump valve area without a lot of fuss. To make the access panel, I first had to let the tank holding pan down so I could make my cuts. To do this, I remove the pan mounting bolts on the driver side, the front and on the rear of the pan. This let the pan drape down so I could get at it with my jig saw. I chose to cut out a section of the holding tank pan and use that cut out section as an access panel. I used a 1" aluminum channel to straddle the cut seam so I could reattache the access panel. In this pic, the grey valve has been removed.
I pop riveted the aluminum channel to the tank pan body:
Here's a pic with the grey valve back in place. Turned out, the OEM mounting flange which connects the holding tank to the valve fell apart from age. I think it was made of styrene plastic. The replacement is PVC
Here's the access panel reinstalled and everything trimmed and ready to go. The access panel can now be removed by taking out about 17 screws and 2 bolts, exposing all the valve assemblies.
Easy to do repairs there from now on!