level editor with 3D tiles.

The way i do it is, first set the number of tiles you will use ie 32*32 then when placing them in the editor have them as seperate surfaces but then create clusters of meshes from the 32*32 tile in game so instead of having 32*32 tiles you will have created clusters of 4+ tiles so onscreen you may only have 2 clusters at most which cuts down on the surfaces
If the cam is static with rotation don't even have backs on the tiles.