CM are working on a 360mm AIO. It's set to cost about twice a normal AIO.
WC, in answer to that, no. The issue is because the TEC outputs 200w of heat on the hot side a 360 is barely enough for a CPU. I mean, you could probably get around it with more rads maybe.....
Problem is these have rubber skirts to stop moisture. So you would also need to come up with a way of doing that on the GPU WB also.