Surrounds for B&W 805 setup

I've doing a 5.1 setup with B&W 805N or S as fronts (with B&W matched centre), and am looking for an appropriate surround, but I have an issue.

I'm in a condo, and the room with the listening/viewing area is 22' across x 30' long. The listening area is in one corner of the space and is about 12' across x 18' long. The wall behind the listening area is about 10-12 feet back, and there's a concrete column on the left rear corner of the listening space (about 10' from the right wall).

Basically, I can't do in-ceilings just behind my listening area because the ceiling is too shallow. I could do them 10' away on the back wall, but I'm not sure if I'll get enough forward throw. The other option is do a wall mounted speaker.

So, I have the following questions:
- would something like the B&W CCM 617 or 618, or the Triad In Ceiling 6 Omni have enough forward throw to get the sound 10-18 feet forward?
- would the Triad Surround Silver On-Wall work well if mounted to the ceiling just behind the listening are?
- Any other recommendations on a speaker that can be mounted 'on wall' and is white to blend in?
- Any recommendations on any other wall-mounted satellites that can be used with the B&W 805 setup?

Ideas, comments or suggestions are helpful.