[jessaustin]

How about just sending the full object state back as the response to my PUT request? Well, according to REST, the body of the response just needs to be a description of the error or success status.

This isn't strictly true:

If the target resource does not have a current representation and the PUT successfully creates one, then the origin server MUST inform the user agent by sending a 201 (Created) response. If the target resource does have a current representation and that representation is successfully modified in accordance with the state of the enclosed representation, then the origin server MUST send either a 200 (OK) or a 204 (No Content) response to indicate successful completion of the request. [0]

Both the 200 and 201 payloads may include anything you want, including a giant representation with many constituent parts (which parts would ideally each contain a link to its respective associated resource).

[0] http://tools.ietf.org/html/rfc7231#page-27