Despite using alot of CEP stuff in my own building, I look to other (usually better) haks for most of my non-wilderness areas. Maxam's Versatile Dungeon and classic Dungeon are among my favorites.CTP, Project Q, NWNCQ and many others can also help round out your choices. Don't be afraid to experiment.
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Another CEP option (not having seen what you are building) might be to use some of the CEP placeable walls either atop of or overlapping your tileset walls to gain extra height and then raise the placeable ceilings to match.