Hey Tyler,
Those 0-3's look great and Black Walnut is one of my favorite woods. I have an entire dinning room set in Black Walnut.
Why do you have them pulled so far into the room? With the ports in the front, you should be able to have them closer to the rear wall. Or, is it because the drivers are on top, which requires the need for excessive amounts of distance from ALL walls ?
As far as moving them around, have you ever thought of decoupling them and putting them on a moveable platform? I have done this to two sets of my speakers and it makes moving them very easy. If my application, I have used two ceramic tiles held together (glazed sides out) by roofing seal tape. The roofing tape makes the tiles dead quiet and free of vibration when tapped by a screw driver. They are almost resonant free too (I'm sure it resonates but it must be at a pretty low frequency since I don't hear it). Another friend used Maple cutting boards and stuck those peel and stick vinyl tiles to the bottom. He said he polished the vinyl tile with some Pledge furniture spray to make them slide even better.
Lou