This is almost exactly to a tee what I did. My best advice is to plan your stand to be able to remove the sump easily. I made my stand using the standard 2x4 frame and the only way I could get the 20l sump into it was by lowering it in from the top. The only way it's coming out without breaking down the entire display is by literally breaking it.
I used the modular Marine ghost overflow with a bean animal drain. Was the best choice of made on this tank, I absolutely love it and endorse it wholeheartedly. I'm also running the same light as you, I'd consider moving up to the 32" fixture if you can swing it. The light coverage drops off significantly towards the sides of my tank with the 24. You can check out my par map attached.
Sent from my Nexus 5X using Tapatalk