Looking good.
Nice training! Have you considered defoliation, removing some of the fan leaves to get more light on the new growth?
Here is a thread with information and a nice how to so you may remove unnecessary leaves with confidence
Increasing yield with defoliation indoors: What's it mean? How to do it?
I have my Mars 1200 pretty close to the ceiling of my veg tent, and my plants are on the floor. Same with my 16's in the flower tent. Seedlings get started on a table, and then when they move into #1 pots, they get set on the floor. Several feet away from the light, no stretching. Plants are growing pretty much exactly the way I want them too.
I think the reason 18-24" is suggested is so all of the spectrums can mix and your plant can get it all. The thought is that is it's too close, the plant might not be getting the full spectrum and you don't really know then what part it's getting.
I like not needing to mess with the light all the time. I have a lot of plants so having the light just set and no need to move it is ideal for me
As you can see I have several feet between the canopy and the light