There should be a forum called "Desperately Seeking Safety Pilot", or something equally cheesy.
So far, I've just paid an instructor to go up and safety pilot for me. Getting a safety pilot is a weird deal for at least two reasons:
1> "hey total stranger, who I most likely am not going to ask to see your license but rather take your word for it; let's go do something that's dangerous. You'll have full access to the flight controls during all phases of the flight. You're not to touch them. I trust you!"
2> I want to go fly; and I need someone to just sit there and look out the window. No, you can't fly. Just look out the window, then go home. Also; I can't pay you, as I understand it, unless you have a commercial license.
2a> I don't like to ask anyone for "favors" (some kind of pride thing going on there); especially from people I don't know.
There should be an article written about SOP in safety piloting: "Hey, good to meet you, I'm Steve; here is my pilot license and photo ID. Today the plan is <blah>. Can I please see your license and stuff?"
So if you can't pay a safety pilot, but you want to compensate them somehow; a flight instructor is a safety pilot who is compensated. I've gone that avenue, and when I go home after the flight, nobody owes anybody anything. It's more expensive, but it's simpler.