Ok, update. I got the camper back today. Haven't had a chance to test the heater yet, but am reserving a camping spot for next week.
Sounds like a lot of the suggestions sort of revolve around what they said they found. I had emailed Suburban and they said they wouldn't give any suggestions to the end user, that the dealer could contact them and they would suggest solutions.
They told me there were two issues. I'm going to believe they tested it, as the thermostat was set at 87 when I got it home! Anyway, they said the delivery of propane was not quite what it should be and that there was oil in the propane regulator (sounds like related issue). They replaced the regulator.
I will update after the camping trip next week.