Right now, my working solution to this problem is separate keys. People want to follow your 130 char tidbits, follow this key, they want your long form, follow another, they want your videos, that's a different key, etc. It's not too cumbersome especially if you pick one (your kind 1 publishing key for example) as your canonical identity with the information on how to follow your other stuff in your kind 0.
To me your approach seems like an elegant alternative, but I'm not enough into the weeds of that trail to give quality feedback.
Well actually I guess you are back to problem 2 that Fiatjaf outlined namely that many microblogging clients would then ignore your other stuff keys. This would be a problem with my solution as well.
In Fiat's solution c, spamming other stuff into type 1 gives the advantage that microblogger apps would appear to suck, if they don't handle these signals in a pretty way (implementing or NIP31 & NIP89 help).