another item you should seriously consider is running a wire from the alternator output stud to the main stud on the starter relay. this is where the positive battery cable attaches to on the starter relay.
this wire should be an 8 or 6 gauge wire with a fusible link at the end that attaches to the starter relay. this will bypass the bulkhead somewhat, and the amp gauge will just show the discharge used by lights, etc. when running.
a volt gauge should then be installed so you can keep track of your charging system.