Options for perimeter of aerial rendering of golf course

I am working with temporary tent structures on a golf course for a tournament and am looking for suggestions on how to handle outside of the perimeter for rendered images and videos. The drone photogrammetry only covers golf course and Sketchup can only handle a portion of the course if I want to be able to add my structures.

This is what a current aerial looks like after I have smoothed, corrected, & “painted” the topography and I don’t like the gray surround:

An HDR file doesn’t work:

Nor does relying on Geolocation . There is obviously a stark difference plus the golf course is currently under construction so the holes in Geolocate image don’t perfectly align with the new course layout.

I mostly rely on videos over still images. Any suggestions?