Luftstalag14
Culé de Celestial Empire
Considering its about name recognition, they could always ask Ajax, PSV, Leeds etc.
I am sure the ESL will be frantically reaching out to clubs if many more clubs come forward and say no, but in the end it doesn't matter who they reach out to to invite, clubs will say no if they don't want to be part of it.
I highly doubt a relatively purist club like Ajax will want to be in.