Step 2: I used the average decimal degrees of the mid-point to geo-locate the model:
Navigating to Wil-Rickenbach, I grabbed the terrain and imported it into SketchUp. I first aligned the Location Snapshot layer to the XYZ surface and then used that to align the Location Terrain to the modified snapshot (using the move and scale tools). The previously imported terrain and texture I left un-scaled:
Closeup of alignment ... compare the 2m grid with Google's:
Using the XYZ surface as a guide, I created a box:
and used it to cut a hole in the Google terrain:
Add XYZ terrain:
BTW, the file-size for this is 200MB.