Mobs per guild with regards to a rotation

[Valoril]

Have you read Divinity's plan? It specifically covers this: if you want to take a shot at the spiroc lord, ask the guild currently clearing sky to help get you up to 5. Sure you'll have to pay 50p each for coffins, but that's not a huge problem. And the Spiroc Lord repops immediately if the guardian is up, so it costs the active guild nothing.

And some subset of the smaller guilds wanted to band together to get a sufficient force, I don't think anyone would have a problem with this either.

I am also 99% sure that it'd be no problem. In the list of the guilds above (BDA, Taken, A-team, Europa, Divinity, Azure guard) I don't see a single one that would IMHO try to be a bastard and disrupt an attempt.
On the contrary, I could rather imagine that most if not all would help with the attempt if desired.