I think you meant /48’s or at least a /63 -- a /64 is meant to be the smallest subnet -- it is not meant to be sub-divided any further. Because some ISPs are allocating /64’s to their customers, I also think a ham-radio allocation would be good.

A /64 would be enough for a radio amateur with a simple network who wants to join a ham-radio network. It would surely not be optimal, but I would not expect an ISP that is that clueless (to allocate a single /64 to their customers) to be willing to route foreign network space to their customers. So what use would it be to have portable address space as a solution for that?

Rob