It appears to take three wise men and a virgin to define your own PAPERSIZE for gs (ghostscript). There is an easy definition in the default system initialization file for all the paper sizes they could think of, but only the -T parameter for the call, and it doesn't seem to work.

When I changed the system file, adding ipad-portrait and ipad-landscape, my page sizing problems went away. But it isn't a portable solution, and I wasted a lot of my fading youth on an Epic Battle trying to get the format right.

(Hmm. Maybe I should right up Epic Battles I have known, some so bad that I remember them 35 years later. Alas, the details have faded, and would probably barely interest a fogy. Now, lessons learned, and things to think about to break out of one, might be interesting....