Fishing weights, that’s clever thinking, I like that.
With the flushing to lower nitrogen, it’s harder to do in no till, because it’s macro nutrients rather than micro nutrients, like with a salt based or organic bottle type nutrient feed. So long as it doesn’t get worse they should be ok.
Thrips fly so they are very mobile, they will move from leaf to leaf, the damage looks worse than it is, but if they get out of hand, they will affect the plants ability to photo synthesis. DE should deter them, they hide in-between the branch and leaf stem, where they join, and under the leaves.
Your temps and humidity is ok that should not be a problem.
The lights are to intense at that distance as the light moves away, the intensity lessens. Different strains handle light intensity differently, and different lights produce different intensity at different heights. That’s a lot of differents
The light manufacturers should have an optimal distance for the height above canopy, usually you can go a bit closer. I would move them up another 6 inches away, if you can and see how they behave, if the plants leaves are up and praying then they are happy.