The pallets were made from wood. Wooden flats are a type of sandal or seedling bed. I think Weitzman was referring to a collection of the same item when he said "flat", so it would be one of the three separate pallet groups.
What Weitzman said is not clearcut, and he later said "I was behind this section of books", not laying face to the floor. Meanwhile, you have Boone, Weitzman and Studebaker lying under oath when they said the Crime Lab photographs show the Carcano in situ.
Are you claiming the Sheriff's Office planted the rifle? No, so far you lack the courage of your convictions. The police had found the shells and there was no report of a man found in or near-to the building with a rifle. Just standard police investigative procedure.
I think he means all the officers on that floor had walked by the location when they arrived. The rifle was fully hidden from anyone at the stairway entrance who arrived from below.
Sure, easy to see if I'm elevated and south of the row of boxes.

Can you see the rifle as you leave the stairwell and walk by the row of boxes?
Cherry-pick.
Mr. BALL. Do you have any pictures of the boxes before they were moved other than those you have showed me?
Mr. STUDEBAKER. Just these two.
Mr. BALL. Just the two that show the cartons, and those are Exhibits A and B?
Mr. STUDEBAKER. We have probably got one down there I can get you that is a lot better print than that. If you want a better print, I can get it for you.
Mr. BALL. Then, you don't have any pictures taken of the boxes before they were moved?
Mr. STUDEBAKER. No.
And it doesn't apply to the NW corner cartons.
Are you claiming the Sheriff's Office planted the rifle?I believe if you'll do a little research, you'll find that it was DPD Captain Fritz who was in charge.....And it was Capt Fritz who said
" Keep looking, I want that rifle and it has to be here somewhere".... Fritz KNEW the rifle was there.....He knew the plot to murder JFK and frame the little commie rat who had defected to Russia a few years prior to Nov 63. Fritz knew the rifle was behind the box with the huge asterisk scrawled on it at the top of the stairs.....