Furnace flame cycling

[A192HWer]

Hi all,
I have a new-to-me A192 HW (2014) and I've noticed that the propane furnace flame cycles. In other words, the furnace comes on from a heating call from the thermostat but after several minutes, the limit switch opens and the flame goes out but the fan remains on as the thermostat is still calling for heat. Once the heat exchanger cools down some, the limit switch closes and the flame comes back. This cycle repeats until the thermostat stops calling for heat. The furnace is a Suburban NT20SEQ. It is the original that came with the trailer. This type is ductless and sits under a dining table bench. I'm pretty sure I know why it is doing this: While the cold air return of the actual furnace is via large slots at the rear of the furnace, the trailer's design for cold air return supply only comes in around the perimeter of the cover for the hot air grill. I don't think the openings around the grill allow for adequate return air. I removed the bench lid and the airflow thru the heat exchanged increased substantially as there were now no restrictions on airflow to the rear of the furnace for the cold air return path. I called Suburban and they said this is acceptable behaviour but I feel this stresses the heat exchanger. I'm considering cutting another vent hole under the bench to allow more air back to the return side of the furnace. Has anyone else come across this and if so, how did you remedy the situation?
I've checked for other restrictions and nothing is blocking the heat exchanger intake or exhaust.
Thanks for any thoughts,
Randy

[Nick Danger]

I just experienced the same issue with my heater over the weekend. Given it was the first time we had used the heater, I thought I was doing something wrong. But from your description I appear to have a similar issue. I have no idea for a solution. The hits just keep coming.