Damned bulkhead connectors.

DON'T DO IT !!! I used terminal strips just like them a few years ago and it was a pain in the *** when something went wrong , and believe me something will go wrong. They don't take well to vibration and jerking around on the wiring. Plus as you mentioned water proofing is another matter. Best bet if you can't afford the right bulkhead connector (they are rediculous priced) go to a junk yard and get one from 80-90s or later car. (you just gotta look for one that will work for you). I ended up with some hi-fi waterproof connector I found on the internet (they advertised NASCAR used them) and they sucked too. Next time I rewire my car I'm gonna take my own advice and go to the junk yard.