The TilingX/TilingY option might be able to fix this!
You should be able to put 0.99... into the Tile X and Tile Y options to get the remapping that you're describing. That way it will remap the [0.0,1.0] domain to [0.0,0.999...] since it multiplies the incoming X and Y component directly.
Does that provide the adjustment you're looking for?