One complication: "The primary purpose of this relay list is to advertise to others, not for configuring one's client." I am in this situation where depending on the client, I have a different list of relays I use (purely by accident, not planned)
Discussion
I think the way it’ll have to be done is to have a core list that seem to be the most popular (this is unfortunate but predictable) and then read kind 10002 and append those to the current list before using.