Mike, looks good!
Three things... switch the LR
Rubble & skimmer. As well, make the baffle between the LR
Rubble and the skimmer higher than the rest of the baffles by at least 2 inches, so you can add more rubble. Also, keep in mind that with your original idea, your water line will be at the red line, not the black one as you drew. So, your heaters will have to be lowered (unless you do what I say... muahaha).
Second... have you determined how much flow you want through your mini fuge? Where it is, it will get 100% flow from the tank. Look at my photo gallery to see my 40 gal
sump. You see how the (future) fuge is on the right side, powered by a dedicated ball valve from my main returns? I just read that fuges should have a 5X or so turnover rate, while the main tank should be at 10-20 X depending on if it's reef or not. It would still be fine, just make sure your macro algae would be fine growing with fast currents.
Lastly, make sure to add in a bubble trap right before your pumps. This way, no micro bubbles can get in.
Overall I would just raise the baffles a bit more on the blue lines, just so your pump chamber doesn't empty as water levels drop from evaporation. Good job!