cgoder,
it's ok to plow with your manual. The trick is to make sure that you don't slip the clutch too much. Cause if you do you'll be changing that thing real quick. I've found that when I plowed with a stick, I either used 2 low(had locking hubs) or 4 low. That keeps you from sliping too much. Also keeps you from building too much speed up and breaking something when you hit it.
WD