If in doubt.......Hang it.
Probably will come out much cleaner looking.
Hanging th eunit also allows you to tune the light for spread while adressing heat concerns at same time.
Start with 16 inch then move down closer and closer untill you begin to get saltcreep on the glass, or the light begins to push too much on the tank's ambient temp.
I am sure legs will also work but you may have to get "creative" so do it safely.