You can also just feed the wires through the existing bulkhead connector after the old wiring terminals have been pulled out. At least one, for your main feed, will have to be reamed a little.
The advantage of doing this is that if you need to yank the harness out of the car, the bulkhead "inner" section will still pull out of the bulkhead, and you'll have a nice large hole where you can pull the rest of the harness through.
In my case, the one plug for the wipers was in good shape, so I just left it alone.
