In general, the simplest explanation works out to be the right one.

After replacing the regulator, I still got little to no gas to the stove, etc. My control panel said the tank was full.

My brainstorm was to remove the "fill level plug". If there was any propane, I should see it and hear it and smell it out of this port.

No propane came out. I got it filled with 10 gallons of LP and the stove and the fridge are happy to play with me again.

So there is an electrical failure mode that will result in the indicator lights saying the tank is full even though it is empty.

Matt

Well, you didn't fix it but you know what's wrong and that's half the battle. For future searchers, I'll say if you run out of LP and re-fill, don't forget to bleed the lines, using the stove is easiest. Turn it on and flick a lighter till it lights. I'm talking older coaches, but most of ours are.