Could I suggest a feature to flag a customer based on wither the name, email, and address?
I tried the tagging system on the "customer" tab but the tag still doesn't show up on the order page's "tag" column.
It would be better if it were a different tag system from the product.
Perhaps I am not understanding your need completely but we have been quite successful using the Automation Rules to flag our customers that require special attention. With the automation rules, we are able to alert the user either with comments, or tags, or just automating the task such as box type, or shipping method, or adding insurance, etc. I know there are tutorials in the shipStation University help area. Maybe you can find some resources there. Hope this helps and good luck!