Well, since no one has an opinion, I'll post what I've done.
I set up three different "system" users (webmaster, postmaster, and abuse) in the forwarding table, but not the user table, for each domain. These three fake users are forwarded to fellow fake user domain_master@myPrimaryDomain. Then domain_master is forwarded to the sysadmin - me. I arranged it this way so that when there is staff change (when I leave), the next admin only has to change one address in the forwarding table instead of all.
I haven't tried it yet, but I think the forwarding table will work with generic address portions such as "webmaster@". This would allow for a smaller table as then there would only be need for (in my case) system entries, eg webmaster@, postmaster@, and abuse@. I intend to test this. If I'm correct, this would be a better arrangement, I think.