region-after (footer) only on last page

Hi,

I would like to have the region-after displayed only on a last page,
when there are multiple pages,but, maybe because of the version (0.20.5)
I get that the 'last-page' option in simple-page-master is not yet
defined (NYI). Is there a way to avoid this problem, to get to the
behaviour I want?

Thank you very much!