I used to work for a service provider, that solved the MPLS administration problem by hijacking 7.0.0.0 DoD space that wasn't publicly routed.
By using 7.x IP assigned loopback interfaces in customer MPLS space, we could export just the loopback interfaces into our managment vrfs (without burning our supply of public IPs.) Of course the one problem is that we'd never have been able to take a Federal contract...
I did a project with a bank where we had to connect our stuff to theirs via a VPN, but they required that the addresses inside the VPN were notionally public - so no 10.x. We borrowed 51.x, which at the time was used by the UK's Department of Work and Pensions but not actually routable. Occasionally new people on the team would ask why the VPN was called VPN-DWP-1.
By using 7.x IP assigned loopback interfaces in customer MPLS space, we could export just the loopback interfaces into our managment vrfs (without burning our supply of public IPs.) Of course the one problem is that we'd never have been able to take a Federal contract...