I've made a program for creating slides using Inkscape:
http://wiki.inkscape.org/wiki/index.php/InkSlide
...of course I discovered the existing one in the same place when I went to post it there, but mine does much more of the work for you.
It's currently very slow because it uses --query-height etc. many times per slide. I filed a RFE
https://sourceforge.net/tracker/index.php?func=detail&aid=1811901&gr...
but I think I could code this into main.cpp well enough myself... if I do that and submit a patch will it probably make it in, or would it be better for someone more familiar with the code base to do it in a way that's more in keeping with other code - assuming that anyone thinks it's worthwhile, and also assuming my patch might be greeted with "why on earth would you do it that way!?" ;-)
Cheers -Terry