A couple of things to remember is that in this day & age, the likelyhood of these bikes setting outside in the weather to rust is very unlikely Most surviving Simplex's are living better now than they ever have in they're lives. The model T cars are in the same boat. The progression for most were:
New & the pride of the owner...probably the first car/motorbike they've ever owned.
Somewhat used....the owner has moved on to better things but can still get some of the value in trade.
Back of the lot (or shed)....most of the good has been wrung out of it.
Teenager transportation....kids get them running just good enough to have fun & abuse them. The end is near.
New again....thankfully it's survived long enough to be found by a collector who brings it back to better than new.
The other thing to remember is a lot of the bikes use the right rear upper bar as the conduit for the tail light wires. Plugging the tubes will prevent that.
Cotton, I'm a 180 degrees from you in reference to Portland. I almost wound up in North Canton a few years ago when my former company moved my department there.
Mike Sal