Regarding the post in the other forum - did you get your monitor panel open?
It just swings open, but may feel like it doesn't budge at first. Mine latches pretty securely, but it does just swing open.
Maybe post a picture of these plugs of which you speak? This is a picture of my 2005 Dolphin behind the monitor panel. You can see the shower plumbing access panels still in place behind it.
GySgt USMC (Ret) '79~'99
2005 National RV Dolphin Limited 5342