I considered this idea at one point, and backed out of it. It seemed like the Referenceable interface would require also adding code to manage references, which wasn't something I was interested in.
But upon taking a second look at it, I was looking at javax.naming.Referenceable, not javax.resource.Referenceable, which extends the first interface, and adds in the ability to set a reference as well. That would likely eliminate the need for me to manage my own references, and sounds like it might be an option. (But it is obnoxious that there are two Referenceable interfaces, and that they are both in javax. I'm sure I'm not the first person to confuse the two.)
Anyway, I'll give that a try, and see what it does. Thanks, Yevgen, for the suggestion.