To investigate further, I decided to employ a simple method using soapy water to detect any leaks. Upon spraying the fittings, I noticed a small bubble emerging from the Orifice of the burner. This led me to speculate that the solenoids on the Gas Valve might be deteriorating, potentially causing inadequate closure. Unfortunately, I was short on time and couldn't delve deeper into the matter.
Taking a proactive approach, I decided to order a new Gas Valve, specifically the "Suburban 161109 OEM RV Water Heater Gas Control Valve." To my relief, this replacement seems to have successfully resolved the issue I was facing. I hope this information proves helpful to others who may encounter similar concerns with their Suburban SW6D water heaters.
Overall, despite the initial complications and the need for component replacements, I appreciate the effectiveness of the Suburban 161109 Gas Control Valve in rectifying the propane odor issue. The improved performance and subsequent peace of mind have been reassuring. I would recommend considering this solution if you encounter similar difficulties with your Suburban SW6D water heater.