One solution to the privacy problem is running OpenWRT with cjdns [1] on the routers and clients, and using its IPTunnel feature [2]. The list of supported platforms is steadily growing [3], and it'd be something that runs alongside the existing IPv4/DHCP setups just fine.

[1] https://github.com/seattlemeshnet/meshbox

[2] https://github.com/cjdelisle/cjdns/tree/master/tunnel

[3] Desktop/Server Linuxes, Android, OpenWRT, OSX, FreeBSD. Even Windows support is being worked on.