Ground paint

It would be nice to have some sort of "ground paint" for laying out your plans, ideally from the git-go. What I envision is simply being able to color individual 'surface-pixels' w/ one of several solid, semi-transparent colors (no detailed decals, though *maybe* hazard or similar fills), so it's sort of like they layout lines they sometimes spray paint on the roads or grass when they're marking where buried lines are. It should be visible, but just tint the existing surface somewhat.
Note that this would be different than laying surfaces in that it doesn't require an even ground shape, but just tints existing ground. Also it conveys *no* advantages like the reduced maintenance of surfaces.
An extension of this is when laying down blueprints, it might be nice to lay down a ground shading for undiscovered/unavailable structures, rather than just leaving them completely blank. Hence you can see where stuff will go in the future.