The XHOs mount to the light itself so on this arrangement it looks Ike you have space to do two reefbrites - one kit on each hydra - which would fill the gaps between lights and add one bar on either end. Or you could get the kit for the kessil and it’ll just have one on either side filling in the gaps in the center. I f you mounted them opposite so it runs perpendicular, you’d have to do it on the kessil in the middle but It definitely looks like you have enough space.
I have the K15 version. They only stick out about 3 inches from the light and are just under 11 inches wide.