My solution was to use a single domain for everything, with different locations broken out under their own subdomains. My colocated rack is "fmt2". VPSs are under normal IATA 3-letter codes. Homes, not just mine, are under "<STREET_NUMBER><STREET_NAME_INITIAL>". Internal services available for all homes are under "int". And so on. There are a bunch of reserved names under each to provide consistent access to per-location devices and services... "network" for a jump-off point to other devices, "edge<N>" for internet-connected routers, "sw<N>" for switches, "svc<N>" for per-location services (Wireguard, DNS, DHCP, NTP, LDAP, RADIUS, BIRD, HTTP/HTTPS, Home Assistant, Home Bridge), "ap<N>" for access points, "print<N>" for document printers, "fdm<N>" for 3D printers, ad nauseum. It's worked great to keep things organized. It also simplifies certificates since I can use wildcards.