That light is doing nicely in there given that it was designed for a smaller space, and the plants are looking lush as well!
Can you bring another sheet of reflective material closer to the plants and hang it so it ends just above the soil? That would kinda replicate something closer to a 2x4 tent with the tubs sticking out beyond at the bottom.
Also, when you do the new space, something other than mylar is recommended as it can create hotspots. Even white paint works really well, to replicate
Panda film.