Well I hope you can squeeze the stand pipe in there and get enough flow. It will take some adjusting I think, but once it is right, you and your reef will be happier. WIth the 2" drains, it gives you more flexibility in how you tune your system, what kinds of strainers you can use, etc. plus of course, being able to keep up with the return pump.
As I may have already stated, I have two sumps, and inbound and an outbound, primarily due to the cunstruction of my catwalk, and the desire to bleed off bubbles before the return pump. I have 2 x 1.5" lines w/vales between the sumps, and a T w/valve just after the return pump. This allows me to keep the water levels in the sumps equalized, and also provides a quick prime if needed.
Because I use the 2" flex PVC from my drains, it's possible to isolate and clean or remove an entire sump, yet keep the system running on just one, and I only allow the water level at 1/2 of sump volume so I can easily absorb any water from an electrical outage or equipment failure.