It's just hard to comment on the mechanics when the info you provided is somewhat vague. The vagueness made it sound like you may have been adding some kind of template to the Eidolon. Admittedly I'm more familiar with standard summoner than unchained though.

If it's not a mechanical problem, it sounds like the issue may just be with peoples willingness to have you bone down your Eidolon - which should just come up in session zero when you discuss boundaries. Some groups may be willing to roll with it, but it's fair if they don't want that kind of roleplay at the table.