Since this is being discussed in other threads, lets put this thread back to purpose.
For a possible Frontierland Expansion this area beyond the rail tracks looks to be where the expansion would happen. The current restrooms building (and some back stage buildings) would have to be leveled, as well as a pond relocated to open up to the land:
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Big Thunder Mountain Railroad train service shop blocks the land further north unless a FL expansion leaves access to go around it at a later date, to connect to another land built across the access canal some day.
This area is roughly 1.5 acres, plenty of room for at least one "E" :
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