Thats what we build all day at work

There is a little product called a Singleator(I think Surly made it) that bolts on in place of the deraileur and takes up the slack. You want to stay away from the High-pivot designs especially, unless you have a tensioner, as these designs are made to 'stretch' the chainstay as they compress. The pedaling force would then pull the suspension back up. Most designs have this effect to an extent because it makes a better sprinter. There have been several designs out there that are drop in for SS. Usually in FS/DH it is not a SS hub, rather an internally geared hub, which is externally the same.