Keith,
The SilverLeaf unit in my coach reads tank levels as well as house battery levels. I am not sure if it is reading them from the CMP 10 monitoring panel, or if it is reading the sensors themselves, but it always seems to work well.
You can call Martin Perlot (888-741-0259), the owner of SilverLeaf, and ask him if your unit has the capability to read the information that you want and what is involved in making it do so, or if you need to try something else. Since Martin's father Mat owned Beaver when your coach was built, he should be very familiar with the monitoring system in your coach.
If parts are not available for your monitoring panel, your other option would be a SeeLeveL monitoring system from Garnet Technologies. Since the SeeLeveL sensors go on the outside of the tank, there are no problems with dirty sensors. Everyone that I know of who has installed the SeeLeveL system is happy with it's performance.
Gerald