I would add a day. Maybe that is the layover at Cave you are thinking of. Small rated camp I believe.
I will try to upload a pic. There is not much at Cave. Not even a ton of shade. July can be hot. This is it.
I am sure you have looked through this site.
Middle Fork Salmon
Let me know your group size and I will give you some ideas. You are pretty much on track though. I love Pungo. One thought is that you have six miles to Sunflower from there and you have to try to stop there. After the hot springs you will still have almost 20 miles to Cave area. Not sure how they classify the hot springs 'camps' you are only supposed to have one and if you are at Trail then you are done. Cow Camp is awesome if not Loon itself and then you have a mile ( 1.5 miles from Cow) to hike up to the springs there. I won't hike a mile in the Sun of July to soak at a hot spring in the heat of day, but if it was close enough to go in the evening that works.
Thoughts banging around my head.....