The horizontal orientation of the ACB12 and ACB20 pockets means that there is almost no room for a canister light. I've successfully utilized the ACB10 weight pouch on the light canister assembly, I end up having to put the light in FRONT of the pocket though, which can become a bit cumbersome if your waist is small. Also if you do choose to try this, use a 9ah canister or smaller. Please check the bolt that holds your light mount adaptor in place regularly as well, because having the light so far forward allows enough leverage/toggle that it can loosen the attachment. the ACB 10 weight pouch won't go anywhere, as it is directly attached to the cinch plate and harness waist is running through, but the light mounting assembly will cause some annoyance if it comes loose.
I have heard of people running the pouches in front of the light canister and locking the kit an kaboodle in place with the buckle (if you've handled the light mounting assembly it becomes clear why the triglide doesn't work the way it would to hold a pocket in place on standard harness, as there is double layer webbing towards the back)
The downward pull and orientation of the larger (ACB12) pockets, and weight pockets combined with a light canister do not allow for the ease of glide that the ACB 10 alone offers. You have to be a bit more conscious of the downward pull when trying to loosen or tighten the via the cinch.
If you are fixing that side anyway with a triglide then that will be less of an issue.
so the long and the short is, for ease of use, it is not recommended to load up the light canister assembly with pocket in addition to light canister, but it is indeed do-able, as long as you are aware of the limitations. if you must use both a weight pocket and canister, use the vertical oriented ACB10 pocket. (I also run 2 13.5ah video packs on the light canister assembly regularly and run into some of the same issues ) If you DO choose to try this configuration, please check the security of the light assembly attachment bolt before each dive.
The better practice would be to use the weight pocket directly on our waist band on the right side, and put the canister light on the waist belt as with a normal harness.