I've come across a seller on Etsy, an "online marketplace" for vintage or handcrafted items. There is a California seller who has some of the older rare parts, not cheap, but about the same rate or a bit less of what items are selling for on ebay.
His shop is small, but he currently has a roof top vent (?hehr,) some bargman handles and a porch light, license plate lights, some vintage trailer name plates and a few other fun things. I've communicated with him and he seems quite nice.
Beautiful Vintage Travel Trailer by VintageTrailerShop on Etsy
I hope this helps someone looking for that hard to find part!
Tina