Hydro Tray Size / Plant spacing

(still in planning stages)

My Hydro setup will use 4' X 8' Grow trays, I am looking at plant spacing (Flowering) at this point.
My current plan is to try to get 10 plants within this space. to grid it out this would leave each plant with approx 19"x24" of grow area, from some things I have seen/read/heard This is acceptable. I will have two lighting fixtures above each tray.
The diagram attached should provide a good visual for what I am looking at.
Is this plant spacing acceptible while flowering? even a large particularly bushy strain?
thank you all

 

EDIT: I am totally rethinking all of this due to the fact that everywhere I look people are recommending at least 12"sq per plant which would change my planning totally.

I have uploaded a new image to throw around some ideas with. I think the 28 site scenario is a bit too ambitious but hey if it will logistically work, then I'm a happy fella