HI Dick,
Yes, that can be done for sure, but you will lose the fidelity of taxiway lights and AI, which will still follow the flat plane attached to the airport. There is currently no way to make the taxiway lights and AI follow the contour of the ground which, according to my discussions with the FS devs at DevCon, is a complex problem and solution. Not impossible, but many calculation-intensive (and performance-intensive) things have to happen under the hood when going from the 2D plane to 3D movements.
That said, yes, your solution is a good one for smaller out-of-the-way airports without much AI or taxiway lights.