Does the Navion have an external propane connection?
My 2106FBS has an LP connection under the frame near the door that I use to run my modified Weber Q Grill. I'm not endorsing nor am I paid and there are likely other places but I bought my Weber refit kit from a company called Propane Gear (propanegear.com). They also carry a lot of other items that you might be able to use to add an additional tap if you don't have one.
I was thinking about doing that but decided against it. The reasons were having a quick disconnect down by the tank filling port. You could plug in the hose and use onboard propane. I did it on my last 32' pull trailer when the kids were growing up. But now I'm checking for leaks on the quick connect. However I'm now thinking having the disposable propane cylinders that are available everywhere would suite me better. I'm in to the KISS program now days. And I love to BBQ and am using a Coleman Road Trip.