Oddly enough, widening the fuse a little doesn't hurt either. Since I went to Ball-Links, I've got into the habit of sticking a tail post in the back when I pinch the fuse sides together to give me more room for the ball link and the adjustment hatch.
Larger fillets with a good material like SuperFil helps too... and it doesn't matter if it's foam or built up, I always use an inner trailing edge doubler. With modern horns you might not have to notch the stab trailing edge spar, but even so, there is a stress riser there and you probably use the brass horn clips that cut into it as well... a hard balsa doubler thats around 6" X 3/8" X the stab thickness, prolly wont hurt. You also get the added benefit of it not cupping (hopefully) when you apply silkspan...
EricV