You're right, there isn't anything in the db that will help.  But we do have our JNDI external url variable that we could throw logic on top of.  I think that gives us "http://marine.usgs.gov/coastalchangehazardsportal" to which we can append "/ui/info/item/{id}".  We would probably actually want the url for this to be /data/qr/info/item/{id} to match and we could support several other schemes (/data/qr/download/item/{id}, /data/qr/item/{id}, etc) for other places a QR code might be cool.