Niantic has suggested splats:
If you can’t do those, you can take geo-tagged photos.
You could try asking help chat (Niantic Wayfarer) to do the location edit where you can give them the extra information instead of submitting in game. And I haven’t done this, but I have been told that the form linked for Wayspot Removals can be used to start a chain of emails where you can supply this evidence. If you use that form, do not reply to the automated email asking for proof you are the property owner and wait for a person to respond.