Putting them in upside down gives a little more meat for cutting joint at the top, and a little more wiggle room if the posts are not lined up. When you use milled lumber, you can set up batterboards and strings and get everything perfectly lined up. These poles taper and working by myself is a challenge. In fact, I had a big oops Saturday. One of the poles fell on my tractor, knocked the muffler off dented the hood and smushed the radiator cap. Luckily the exhaust manifold is ok, and the radiator neck is ok. I just spent 1,000 getting the radiator rebuilt last summer. I think I can pop the dent out with a mallet. I need to repaint the hood anyway. One thing is for sure, a 1962 Deere 4010 has a pretty solid hood!