I think this technique is wonderful, and will surely implement it as I do my work! As long as a person does only very rough additions, just to get the idea if something will work right, or look good, this is a great way to set up the gameplay.
Once the ideas and levels are all in place, then it's time to create the good models and textures.
The domes are a great idea too, and i have done something similar to guage what the LOD should be in a particular level.
I don't nee to see the shaders now, i can already see with those basics how things could look
Great work!
- Jason