qconfirm, SPF and Pobox.com?

Hello,

I complained some time ago about Pobox.com going to SPF and SRS. For 
the moment, I'm not angry enough to switch providers, but am thinking 
about reversing their obnoxious anti-spam measure. I can think of two 
ways to do it:

1) Write a qmail-queue wrapper which un-munges the envelope sender. 
This would not be too difficult.

2) Teach qconfirm how to un-munge for the purposes of checking. This 
seems much more painful.

The only problem I see with #1 is multiply-rewritten envelope senders. 
So far I've never seen such a thing in the wild. Also, minor annoyances 
might arise with emails from pobox.com itself, but I don't care about 
that.

The first big problem with #2 is that we would also have to deal with 
the recipients of confirmation messages; we would either go through the 
bounce mechanism at pobox (by using the munged envelope sender), or 
directly by using the un-munged sender.

Any thoughts or suggestions? Anyone else dealing with a situation in 
which they can't easily get out from under a use of SPF?

Thanks!
Len.