Hello,
if the mesh is complicated, always use SEO. Because editing nods after hole is trimmed, would be confusing. Using hidden 3D "trimmer" should be much easier.
Then ground is plain, just trim the hole using "magic wand" and foundation ghost story.
SEO function is a life, changing house location, the hole move along.
But You will miss some lines in section elevation (for example there foundation intersects ground )