Sorry, I overlooked your question. 360 Hunting Blinds starts their opening 24" off the floor and goes 30" high for the actual opening size. With a 6'1" wall height to the ceiling that size allows 19" to slide the double sliding panes above the opening. (They do a small fixed window in that 19" for something to see out if you are standing up) The plexiglass double sliding panes should be 16" high to cover the 30" opening with a 1" overlap. Note their system of blocks attached to the plexiglas to slide the double panels open with one string and weight. the upper block has a gap in the middle to allow the string to pass through to go on down and attach to the lower block. When you pull the string to open the window, the bottom pane slides up halfway across the opening then it hits the block on the upper pane and pushes it along the rest of the way up. This is a very smooth and quiet system.
This window height works for standing or sitting. Taller archery windows like this are usually around 10-12" wide.