RG,
I don't know NoCams, but he knows of what he speaks! He's 100% right on the Grade 8 bolts(don't settle for Gr-5)especially if you go longer. A WP only allows a max cut depth of 2.25 inches(including bark, so that's 3.75 inches of step remaining. 2.25 inches is only suitable in my opinion for live hardwoods (oak, hickory, beech, ash, iron wood, hackberry, etc) and only because they have relatively thin bark.
I'd want a 4-inch cut-depth minimum in a pine w/a 3/8" diam bolt; might go 3.5" with 7/16" or 1/2" diam bolt, AND NO MORE than 4 inches (like NoCams said) for the step (too much leverage to bend one and tear one out of the tree. You have to realize this method is NOT the same a SCREW-IN Step. These bolts are NOT forced into the wood, but slid in (in a bigger hole) so it can slip or tear out easier than screw-in steps. Again, NoCams knows of what he speaks - heed his words for your safety.
In the soft-wood (pine) situation, the WP or Woody Drill would not be worth it (to me) going that deep (4 inches) because it's just too much hand-drilling effort. I'd just use the longer screw-in steps (like Matt Quick said) if close to bedding area on a first-time hunt, or a 12V lithium mini-drill if further away or setting up days/weeks in advance.
Just don't buy 10" Gr-8 bolts (for pines) and cut off 2" of the ends (threads) because you bought them too long. If you need shorter bolts for pines, trash the 10" ones and buy 8" with the treads intact. Or buy 6" with threads for hardwoods. The threads help grab the tree-grain and stay in the drilled holes better - you and your loved ones will appreciate that.
Don't need to be a machinist to make one. Use an 8" length of alumimum "C" channel, 1/8 inch drill bit, 1/8 inch roll pin or bolt w/lock nut, 3/8" diam dewalt/Irwin self-feeding bit, 3/4 inch section of alum arrow (for a spacer), a 1/4" bit depth stop, a 2" long,thicker walled alum tubing, a plastic/wooden handle with machine screw/bolt/locknuts/washers, an electric drill, hacksaw, flat-file, and a couple of hours.
NoCams - Great ideas, man! I have an SOP too, and never thought about using it's pouch that way. How do you use your prussic/tree-rope (specifially) as your lineman's rope? (carabiner? with extra loop(s) tied in?? ) please explain. I actually have some plasti-dip in the garage - great ideas!
I love this site - great people and resources.