Looked briefly, this thread http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25168579.cfm
Makes it sounds as cable has full sheath and is attached to the valve(s)? Sounds like you verified. Short of Lance responding, and not second guessing might look at that if you can see/access. It also sounds as though bottom removal doable, possibly an access panel on the 1181. I assume nothing behind that can be easily disconnect. But it does appear access to valves required.
Mine Id be circumventing need to remove the bottom, IF valve access could be had with panel removed. In that case, with everything else loose verifying only the sheaths are holding, possibly deep hole saw to cut around the hex on old panel. Redrill the new panel so sheaths can pass thru, use slotted washers to recapture, since your backing up panel anyway. But removing bottom or whatever is needed might in the long run be easier, then its do you replace the valve while your there?