I can appreciate the idea of taking a scientific approach on this.
If you want to approach it that way, I'd suggest engaging a botanist who can help you figure out what the true effects of wrapping anything around a tree will be. They'd probably be able to help you come up with a method for testing the damage done to various types of trees (hardwood, softwood, bark types, etc...) in various conditions (frozen, blooming, etc...).
Once you understand those effects, you can determine what the most effective way to disperse the forces created by hanging across the widest/most appropriate area to protect the tree. (I don't view LENGTH of strap as a nearly a critical factor as WIDTH of strap, for example).
For example...would it be possible to skip using webbing altogether, and instead use a much wider section of material, like the nylon used in a tarp, to wrap around the tree trunk and displace that force evenly over a much wider area, reducing the possible damage?
It would stand to reason that the remaining factors...those calculated by the 'hang calculators' out there, would demonstrate the best angles to hang at to minimize the amount of force generated by a hammocker. So, setting that 30deg angle and minimizing movement in the hammock to reduce static spikes in force would be another way to work on this.
Maybe some kind of shock absorber/tensioner built into the suspension to reduce/prevent transmission of those force spikes to the tree? Like an extremely short/strong section of shock cord type material (think bungee) that would only stretch under forces greater than the normal forces when someone hangs still?