Of course another way to go is to have SK Grimes fabricate a step-up ring that will accept modern threaded filters--that way you can use pinch-caps or the appropriate Kaiser push-on cap. That's the way I went, with the rationalization that the typical RDA is such a good "bang-for-the-buck" option optically that pimping one out is just playing with house money.
That said, I did buy an Ektanon from LA-based photographer Andrew Glover (an experience I heartily recommend, just for the jokes) that had a cap from a Pringles can protecting the rear element, so field expedient solutions are available.
Bookmarks