One of the exercises I've found really effective for getting the hand locked in together is this one from Gavin Harrison in an old, old issue of rhythm magazine:It can definitely get awkward, especially if you don't work with it. I personally have difficulty ghosting with my left hand when I do play grooves like that.
1) Sixteenths on RH for one bar
2) Sixteenths with both hands for one bar
3) Sixteenths on LH for one bar
4) Sixteenths with both hands for one bar
(Just to clarify when I say "both hands" I mean in unison, as opposed to alternate)
You loop the four bar sequence and focus on getting the unison hits landing together with no flam in between, the aim is also to keep everything the same dynamic level.
You then take the excercise through it's permeutations (sp?) in terms of dynamics: RH - forte, unison and LH - piano for example and all the other combinations thereof.
After getting that down practice constant sixteenths with the RH and improvise or read patterns for the left (patterns from syncopation are what I used) and focus again on getting the unison notes coming down cleanley together and after that mix up the dynamic of the LH patterns.
I noticed even after a short period of time that these excercises were paying dividends for me, I was able to free up my right hand (I'm a open handed lefty) when doing one-hand 16th grooves and it tightened up my accuracy, groove and feel in general. I still practice it everyday as part of my routine too...probably one of the most important parts of my routine come to think of it.
Anyway, I hope that's of some help,