I've never bought a bar harness as I use my myog one and I've been very happy with it. When i was using rigid forks I had a small aluminium tube running horizontally across the fork crown to which I attached the bottom part of the harness. This served to push the harness forwards so as to avoid my dry bag rubbing on the head tube. However, when I fitted sus forks I couldn't use the cross piece as the fork brace would hit it on compression. I have now fashioned a piece of 3mm thick plastic card that you can get from modelling shops and attached it to the harness so that when you put a bag in and tighten it all up the card stops any rubbing as it does not flex enough to allow contact between the head tube and bar bag.
Card mounted on harness.
https://flic.kr/p/2jp2HUq
Bar bag in harness showing gap between it and the head tube.
https://flic.kr/p/2jp1vgA

Hi, a simple an effective solution,
I made A support and bar harness combined
I took inspiration from the Alpkit Kanga.and Revelate Sweet-roll. It all integrated into harness. It's unique very solid on the bike tempts you not to TakeLessStuff

Well done in finding a light and simple solution.