I was thinking of something along these lines. It looks like the paddedlumbar support on a standard climbing belt is 5". I'm guessing that's enough to support your weight without it painfullydigging into your back.

with just a plain-jane climbing strap like this one:

This way, I can use the tool loops in the belt to carry steps/step installation equipment/pruners/saw without having to make so many trips up and down the tree.

Do any of you guys use anything like this? If you're a good climber, do you even need a secondary harness attached to the tree?

I'm a really good climber, but I just get nervous when I'm fumbling with trying to re-thread the safety belt buckleseverytime I need to get around a limb. With the carabining clips, it will be just a simple unclip, reclip job. You could even use two straps, taking one over the limb at a time, eh?