I would suggest keeping the cleaning to a minimum, and something like a sand sifting star just defeats the purpose (and benefit) of having the DSB to begin with because the star will destroy and the microfauna that inhabit said DSB.
What I did with mine was clean a small portion on water change day - maybe 1/4 total area or less using a python siphon to get down deep. All that did was remove the nasty gunk, leaving all the micro brittle stars/etc behind to do their jobs.
The nassarius snails are a perfect addition for a DSB. The sand sifting goby will be fine as well, although they can make the rest of the tank a bit messy with all the sand they move around. (I like them btw). You will need a good fitting screen top on the tank with the goby however - I finally gave up on them because the DSB I had for my 150 it was impossible to keep them in even with screen tops. They found the tiny openings for plumbing and out they'd go.
The DIY screen tops made from BRS 1/4" netting and window screen frame parts from HD/Lowes are the best I have ever used. I cannot imagine a tank without.