"Actually, we do not know that Deck 8 is in the Engineering Hull.
We just know in "I, Mudd" that the Aux Control Room is on Deck 8."
Fair enough. But then please forgive my inevitable question where you are going to put it in your plans / cutaway?
"Some items to consider: ... When Scotty and co descend down the ladder, we do not know what intervening decks they passed through to appear in the engineering room's upper level. They do not exit from same type of ladder they descend in."
As it appears the turbolifts on the Constellation
don't work, therefore the landing party has to use ladders instead. But Scotty does exit from the same type of ladder when he reappears: They climb down http://tos.trekcore.com/hd/albums/2x...hinehd0206.jpg
and Scotty surfaces later in the exact same section: http://tos.trekcore.com/hd/albums/2x...hinehd0238.jpg
Since the bridge of the Constellation
has been destroyed and there is severe structural damage to the saucer hull (both TOS and TOS-R) I'd find it rather difficult to imagine that what we see here takes place in the saucer. This would imply that Scotty and party descend from deck 5 to the upper level of the engine room, but Scotty has to come back up to deck 5 - only to climb down again the next minute to deck 8 where they finally arrive at the Auxilary Control Room which seemed to be a place they needed to go anyway to find out what happened: http://tos.trekcore.com/hd/albums/2x...hinehd0253.jpg