UPDATE!! It's not the gas tank
OP here! Thanks for all the great replies. DH tried firing up the heater today and couldn't get the fan to run more than 30 seconds before shutting off. The stovetop does work so there is gas and it's getting to the trailer. He opened up the heater and for some reason it's not even sparking in the heater. DH started a thread, "heater problem".
He called the dealer and we're taking it over first thing in the morning. They're hoping it's a bad circuit board, which they can quickly replace. If not, we have to button it back up and bring it home because we're leaving Thurs morning for a 5-day trip to the Poconos. I hope this works!
Jen & Fred plus 3
2009 Rockwood 8317SS
2008 Ford F150