Re: Labels people, and read them!
If the DHCP server (windows, 'nix, etc.) doesn't support HA, you split the damn scope, like the best practices state. It's not that hard.
FWIW, Server 2012 R2's DHCP server does support HA, although it takes a bit of effort to set it up.
And also. LABEL THY PRODUCTION SERVERS. Even if it means you print a label out of paper and cellotape it to the front of the server.