Since you will have a canopy and since your tank has a trim, you could almost try the Calfo style return manifold as seen here:
I used this briefly on my current tank, but decided to go with something else later on since I was running an open top and all the pipes were visible. If you do it correctly, all the pipes can be easily hidden. I have mine hooked up to a SCWD wavemaker as well so that only 1/2 of the manifold would fire at one time. It worked beautifully. I would be cool if you could use 2 of those manifolds...one on the top of the tank, the other under your sand bed...
The problem with getting the right water movement is that it all depends on how you set up your rocks. Basically, you just want to avoid dead spots as much as possible.