I think this indirection should always exist, not just when a section is overloaded.
The hash of an ID chunk or an MD name wouldn’t be the address of the data anymore but would be the address of an indirection element that gives the real address of the data. This final address would be computed from the hash of the initial address concatenated with an invariant of the section, agreed between data managers at creation time (possibly rehashed several times until the destination section is far enough).
This indirection would also solve the problem of data managers storing data whose id is the same one that is needed to get the data. An attack to get free safecoins is currently easy: launch a vault and a client program that issues GET requests over the ids stored in the vault.
Three years ago there was a topic about it. Gaming the farming reward. AFAIK this hasn’t been solved yet.