This is kind of a "Co-GM-Lite" request. Given that Realm Works was built from the ground-up with the concept of having one GM in control of everything, I understand that changing that might be a logistical nightmare. That being said, would it be difficult to allow a specified invitee to just view everything, revealed or not?
Then they can communicate suggestions/edits/ideas/whatever by other means (email, instant message, video conference, et al).
Then they can communicate suggestions/edits/ideas/whatever by other means (email, instant message, video conference, et al).