I am also a person that does not frequent gun shows, but I make a habit of understadning the law in my state (WA) and neighboring states I may be in.
In OR, there is no "gun show loophole" The state legislature closed that years ago. However, private sales, between private parties are unregulated.
There is a section in the law that you "MAY" follow, that will allow a private person doing a private sale (not a a gun show) that allows for the private person to have a BGC done on the purchaser, and the purchaser "MAY" do a stolen items check on the weapon. These are not required, but they are available.
Here in WA, if the gun show allows (some here do not) a private person can sell at a gun show, or privately, without license, BGC, or stolen weapons check. As I have stated, some of the gun show sponsers will not allow private individuals to sell firearms at their shows, but it is not state law. WA also has a "report of sale" available for private transactions, if the seller wishes to use this, but the state's real interest is in collecting their sales/use tax, not regulating or registering weapons.