What are you running the cables in? I've got D-Line trunking with back boxes of I think 28mm, the trunking fits in with the back box perfectly through a semicircle T-shaped connector into a semicircle in the back box so it keeps things much neater. It's a while since I ran any cables so I'm not sure if it's still available but well worth a look. I think various depths were available which could prove handy for different modules as I do remember some being a bit of a challenge to line up cables (so get a lot of tiny cable ties). I bought mine from Screwfix and it really was money well spent, the only issue I found was with the trunking was with the adhesive backing which stuck to the wall for about ten minutes before falling off so screwing it into place was easier, especially seeing as the back boxes were screwed into place anyway.