I run the stove hood and crack open the cealing fan. That will create a downdraft of outside fresh air to pass around the smoke detector.
One thing I noticed.... the camper is so air tight that you need one fan running, a cracked open window and/or a fan open on the off position; both fans open, a window needs to be open for the air to flow. Running without anthing open but the fans, will create a "vacuum" and the air inside does not move. I have dual fans; one up front and one in the bathroom on my 2306. The bathroom fan, running at full blast, will move enough air to make the front fan spin pretty fast, when the vent is wide open.
2016 Rockwood 2306
2016 Chevy Colorado Z82 / 2009 Pontiac G8 GT