I have applied some of the landscape changes to the portrait file copy as well.
However, during testing of adding the due date into the footer, I ran into a snag related to the footer (and contents) that could become a potential issue. Now I'll have to double-check the landscape footer too.
Yesterday, after a few hours of "fighting" the PDF layout/handling, as it seems to take sometimes [at least for me
], I did get the appearance to be as expected. However, there are two fields that can have quite a bit of output, because the footer can have a romalpa , 'invtext', terms, due date, and account info, the first two fields can be problematic.
I'll post a separate topic to the development discussion with the issue, and a proposed change that could help.