One thing to consider as you are considering baffle height is that the baffle height will determine the water level in the sump (except for the return pump chamber, of course. The water level there will be determined by evaporation).
The higher the baffles the higher the water level in the sump and the more water in your system overall. However, you also need to consider how much water will drain into the sump when the return pumps are off, especially since you will have two tanks draining into the sump... the DT and the fuge. If the baffles are too high then there won’t be enough space for the water that drains down into the sump and it will overflow when the pumps are shut off.
The other thing you might want to consider is your skimmer. Most internal skimmers have a specific depth that they are designed to work at, so you want to make sure that the water level in your sump matches the water level that your skimmer is designed to work with. If the sump water level is deeper than what the skimmer is designed for, then you can easily elevate the skimmer on a little platform, but if the sump water level is lower than what the skimmer is designed for then there is nothing you can do and your skimmer will never perform well.
