Its a little hard to see what you’re trying to achieve with all the scribbles. But if I’m understanding, you just want to change the texture inside the hole? And it seems like that is the landscape peeking through the middle of the hole?
If its the landscape there, you can either use a decal, or draw a mesh into the virtual texture (which can be done even if it is not drawn in the main pass). Both of these can overwrite the landscape and show whatever texture you want.
This video demonstrates using both a plane to write into the RVT and a decal to pass along data to alter the landscape material.