Casey, Dan,
Getting a mesh for games/real time visualization in SketchUp is quite easy, but it requires knowing what and how to use certain extensions. The process is not complicated, but it requires on the one hand a few clicks in Add Location to expand the area you want, and on the other hand, a few more clicks in creating the low poly terrain and a single texture (2-4-8k) from the imported tiles (over a hundred) and then texturing the resulting terrain.
Or another possible method, using a height map to generate the terrain.
It would be useful, and probably not only for such extreme cases with extremely large surfaces, to be able to obtain directly from the Add Location process, a low poly terrain with a single texture (or a few), as an option, in addition to the current result - terrain created from many tiles, each of which in turn with many polygons and each of these with their own texture.
See the discussions and solutions in these previous threads.