This morning I called Onan/Cummins customer support and had them check for TSB's for this problem on my model and S/N of generator and they could find none.
At the recomendation of a shop in the twin cities area that does a lot of propane work and sells lotos of kits and parts I did several more tests.
I tested the demand regulator by checking it for flow with the hose disconnected from the carb, some spit over the end of the hose and with the tank valve on and the fuel shut off solenoid energized and there is no flow.
Then I tried clamping down on the hose between the demand regulator and the carb, and I can make it run properly. This supplier in the twin cities offers an adjustable flow outlet fitting for the demand regulator. Here is a link to this part.
https://carbturbo.com/product/33-ea-fitting/
While this may not be a "by the book" repair, I think it makes the most sense to try this next. My only concern with this fix is if the mixture will be close enough at all loads. The tech person at this supplier said this fitting is made for this purpose and felt it would be fine.
I will report back once I get this fitting installed and do some test runs.
Thanks!