I interpret your definition of "slammed stem" as a cut out in the head tube where the top of the stem is inline with the top tube. Like a Plasma TT or Shiv TT.
I think your best bet is a bento with a rounded front, like Dark Speed Works or Xlab model. Take a look at Vesterby's SuperSlice from this year.
http://www.tririg.com/...uper_Slice&num=8 Or, if you run no spacers and a BTA bottle, then you may be able to butt the bento up against the back of the bottle. May have to put new holes in the bento to allow it to bolt further forward and overlap the stem.
Alex Arman
Strava