I dropped the forward coroplast under the black and grey tanks last October to replace the black tank valve seals. Not a hard job.
After replacing the seals I made lube holes as in the video.
THIS WORKS !!!!
I tested it first on my Valterra twist on gate valve. I can now open and close all the valves with one finger.
While I had the bottom off I sealed up any holes in the frame (air gaps) with Gorilla tape to stop any drafts (keeps you warmer/cooler). I also installed insulation around the perimeter and across the bottom before putting the coroplast back up.
SmartSHIELD 20mm Reflective Insulation Roll
https://a.co/d/baijHZq
Valve lubrication making lube holes for silicon grease