I have good news. I have been going out and filling up my black tank then flushing it to fully dump it twice a day. I did not do this because the tank was full, to the contrary it wasn't even at a 10% level according to my digital display level indicators.

Thanks to some online iRV2 fellow Fleetwood Bounder owners I found that the enabling signal that stopped (in their case the VACUFLUSH, Fleetwood replaced them with macerators around 2020-21) the macerator and flush was coming up to both toilets on a yellow wire. This yellow wire is normally OFF and when the defective sensor or float valve turns the signal ON it prevents the macerator from turning on and the water from flushing. This signal is suppose to prevent overflow from a full tank, except when the indicator is defective, which is what the case was with our Bounder. 

So the easiest path for fixing the problem was to put a single pole ON/OFF switch in the yellow wire, and leaving the switch OFF. The right switch can be easily mounted to the plastic side panel of the toilet. The digital display level indicator is working and I will be able to monitor the tank level from there. I am so happy. I hope this post helps other Bounder owners with the same problem.

To find what sensor or other part that was signaling the wrong full level would of been a much harder task to accomplish. It would of involved crawling inside the bay adjacent to the black tank, removing an access cover and trying to find which one of the sensors was defective and replace it.