Another curling/border question

[NancyBC]

HI Everyone,
I've agreed to do a blanket that will be 50X80 for a friend who just wants a wool layer while camping in his sleeping bag. I'm going to use Sean Sheep 75% wool and 25% acrylic with one strand of Sean Sheep 100% wool. I know I'll be cross-eyed and crabby for most of it!
StSt is the smoothest but even with KPKPK borders and sides I can see it curling like crazy. I sure would appreciate easy suggestions for the body (K1P1?) that would be smooth and perhaps another border idea. I'll do 5 rows top and bottom and at least 5 or 10 stitches on the sides.
Perhaps he'll change his mind.... or I'll stop volunteering before I know the details-lol.
Thanks a million in advance!
Nancy