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