Hi csxengineer:
Sorry to disappoint, but maybe not. 2.5 miles is 82.5 feet in N scale (2.5 x 5280 / 160), but that's track length, not square feet. An 8' x 10' layout square is 36' around the 4 edges once, not 82.5'.
To get 80' around the room square is 20' each wall times 4 walls...