Yep, lots of threads on this if you dig around on IIS. Definitely worth trying to move the mirror up a bit first before you get too carried away.
Another option aspiring Newt imagers have to consider now is the
Baader Rowe coma corrector. Peter Ridgeway showed me one recently, but I haven't played with it at all. In theory, looks nice - gives 91.5mm backfocus if you can get it into position properly in the focuser. I think the more common Baader MPCC helps a little with backfocus too.