Angles and support will help with regard to ankle stress.
All the tweaking you can do to angles and support will pale in comparison to force applied over time. Put simply, you're tinkering with 10% of the pain by changing boots or platforms, or types of soft saddles.
The best I could do when primarily using the kestrel prior to the JX3 was keeping my ankles, knees, and hips at exact same angle, with me about 45* off the tree. This put something like 30% of the stress on my ankles/feet. I could handle it just fine. But handle it, and it being comfortable are two different things.
In the hybrid, I have 0-30% of my weight on my ankles, and can make micro adjustments instantly with hardly any movement. And I'm comfortable doing so, because the force of my body weight is spread from just above my knees, all the way up to my shoulder blades. No soft saddle can come remotely close to this.
You may not need to go to a hybrid because you might find a middle ground that works. But I suspect it will take a stroke of luck, or a LOT of trying things out to figure it out.