I have a situation where there two NEMA 3R enclosures in a wet location are only 1/2" to an 1" appart and the wiring will feed through a knockout in the back of the first enclosure to the knockout in the back of second one. Since the distance is so small, instead of using a conduit run, my thought is to use a rigid steel nipple with sealing locknuts on the exterior of both enclosures and regular locknuts on the interior to make the connection liquid tight. Is this acceptable?