1" return off the durso might be noisy and is pretty small. Your going to have to play with the size off the 1" if that the biggest you can get. I have 1 1/2 durso all the way to my sump, dead quiet with a 1" return off a panworld. U sure you can't get a larger bulkhead in?
I only have one return, but I have a dual float (two separate channels) in the overflow to my RKE for fail safe on overflows. If a single durso, you need to make sure that it does not siphon and can be as fail safe as you can get. If for instance, something breaks loose and goes into overflow to plug durso, your going to have overflow. If you can get another failsafe drain to fit in, it would be good, simple to do with a straight shot to the sump.