Ditto on all the good advice, I've owned Summit, API and now a Timbertall Climbing Treestand and they all are great! Check out http://www.treestand.com they seem to be the online authority on treestands, parts, accessories and advice!
For all the effort and expense you have to go through to make one, why not buy a solidly built Gorilla 49 dollar loc on at Wally World????
Tell you a little story about homemade loc ons. A hunt club member of ours graciously offerred to supply a half dozen bowhunting loc ons one year. A month before the season there we were hanging stands. The member was trimming a few high limbs above the stand for head and bow clearance when all the sudden the platform gave way and he was left hanging from his safety harness.
Trouble was.......low grade bolt mixed into the high grade bolt bin. The bolt sheered off cleanly. Had he not been in safety gear, he would have fell 25 feet.
Wood stands.... Thats just plum crazy anymore given the excellent and affordable options out there.
As a Taxidermist I look at hundreds of Whitetail Bucks every year. I know that I have seen many different ways people judge the size of racks on live deer. I think for the most part they all are pretty close. I'm going to give you some measurements that I have noticed being right on in just about every deer. We have used it in the last couple years and have only been off by about 5-6 inches. We do study the deer while bowhunting so we get a little more time to look at them....