The way you have them, the skimmer area will fill tot he same level as the center section. Although that isn't necessarily a bad thing, you'll need to make a platform to set the skimmer on. Most seem to work best in +/- 8" or so.
I think you are underestimating the amount of back flow from the DT, and will have very little room for error with them as high as they appear to be. I would suggest aiming for the sump to be ~ 1/2 full while in operation.