I would like to create a mass-market paperback size book using scrbook. The book in question is approximately 400 pages long at 6x9 dimensions. I would like the text to still be readable, but I'd like this version to have as few pages as possible. What packages are recommended, or what techniques/tricks can be used to best accomplish this?
I tried to search the site for answer, but I am caught in a captcha infinite loop. The first two or three times there were pictures, now I just check a box before I get yet another captcha. Hence this question.
\documentclass[fontsize=10pt,headings=small,BCOR=.25mm,openany]{scrbook}
\usepackage[paperheight=6.88in,paperwidth=4.25in, left=1cm]{geometry}
% will the binding correction affect the margins?
\addtokomafont{disposition}{\rmfamily}
\usepackage[english]{babel}
\usepackage[DIV=15]{typearea}
\usepackage{fontspec,xltxtra,xunicode}
\defaultfontfeatures{Mapping=tex-text}
\setromanfont[Mapping=tex-text]{Times NR Condensed}
\linespread{.9}
\raggedbottom
\begin{document}
blah blah
\end{document}
The following lines were deleted because LaTeX reported that they were causing conflicts with scrbook. It's odd the crop package caused a conflict.
%\usepackage[small,compact]{titlesec} %added to save space
%\enlargethispage* %added to save space? didn’t work
%\enlargethispage{3\baselineskip}
%\usepackage[cam,a4,center]{crop}
I tried reducing the font to 8 pts but it's really not readable. Are there any other suggestions, or packages that might help?

typeareaandgeometry. All thetypeareastuff is done while/after loading the class, so any changes afterwards need a recalculation. Issuerecalctypearea. – Johannes_B Apr 29 '15 at 09:50