I'd say one of those light is good enough for a 4x3-4x4 area. I'd do an 8x7 area in that trailer for flower with those 4 lights. You could grow 16 plants very easily. Then assemble a 4x4 room for veg (hopefully you have more lights for vegging).
I have a Wild Thai growing under some COBs. It's a beautiful plant and branches like Gorilla Glue. I'll take a pic tonight and post it here.
EDIT: it's at 38 days from flip
I've not added anything other than water. The SS cooked for 8 weeks. I weigh and measure everything according to the recipe. FWIW, it's only on a few plants and it's not very abundant.