With the endpoints that @jdsilva mentioned, it's pretty easy to figure out which networks don't have floor plans:
1. Get your org ID
2. use getOrganizationNetworks to build a list of networks
3. Run getFloorplans on all networks with a loop.
If the return is null, you've got no floorplan. You can output the no-floorplan network names to a file and then boom, checklist!