hi tim,
i've done this a bunch of times, simplicity is the best way! i use a spreader bar on top wide enough to keep to bungees away from the camera body. on the bottom plate use solid stand-offs of around 5" to keep a good centre of gravity with one bungee on each side of the camera.
on a fisher i always put a rotating off-set then a foot and a half of risers then a twin tube paddle mount and hang the bungee on the end, it works really well to keep the rotating off-set unlocked in shot for small moves left, right or in, out.