Would it be possible to do this based on MAC? Vagrant has that info, at least for the first interface since its interaction with VirtualBox relies on sharing that piece of info:

    env[:machine].provider.driver.set_mac_address(env[:machine].config.vm.base_mac)

from https://github.com/mitchellh/vagrant/blob/master/plugins/providers/virtualbox/action/match_mac_address.rb

Although I don't know exactly how that information would be available from our plugin or how interfaces after the first one are handled.