It is unlawful according to Oregon code to carry any 'loaded' firearm while on an ATV, I think this includes even your pickup if your off-roading. I don't know if anyone has ever challenged it, if they have its been unsuccessfully.
Without PC or RAS no LEO or pine pig can search you legally, and since Carry is not PC or RAS and your not doing anything else illegal who's gonna know if you got one in the chamber provided there's no mag in the sidearm? And if your searched on the grounds of OC itself any evidence found should
be thrown out of court.
Not that I'm advocating violating an unconstitutional law that is to be treated null and void.