You probably want something like a homemade T-bar you can clip the CSB's on. With Omni's, you want a bit of separation. At least a foot, probably 2'. It could be a wooden stick, or a coat hanger, or whatever you want. Many festivals have an Official (or unofficial) taper's section next to the SBD. If it exists, I generally use it. if not, than go where you want. If you block the sightlines of the sound or lights guy, they will yell at you, but you probably won't be that high.
Omnis have the benefit of not being as sensitive to wind as cards, but you still need windscreens. You can probably find something here...
http://www.olsenaudio.com/general.html Olsen makes them, but doesn't sell direct. Once you find the right model number, then you go find a seller. Your CSB's are 1/4" in dia, so that's your inside dimension. Find the fatest OD you can. And don't be surprised if you need something over that, like dead rats, or heavy socks.
What do you do if it rains? You need an umbrella. Probably the easiest thing to do is abort the split omni bar, and go clip to some other taper's t-bar under his umbrella.
If you are running from you own stand, you need to stake it down with tent pegs so the wind doesn't blow it over. Or weight it down with rocks, or something.