"Minimal" LaTeX export

[Vicente Vera <vicentemvp@gmail.com>]

Hello

I'm trying to export a simple document to a LaTeX buffer, but just the
main content, without a preamble nor the "document" environment. The
main objective is to export several Org documents which are parts of a
larger LaTeX report. These parts are then included by means of the
"input" command.

This is what I came up with, but, of course, there are other functions
involved that seem too expensive to modify:

(defun this-is-just-a-test ()
  (interactive)
  (require 'ox-latex)
  (let ((org-export-with-date nil)
        (org-export-with-toc nil)
        (org-latex-classes
         (append org-latex-classes
                 '(("nothing-at-all"
                    "[NO-DEFAULT-PACKAGES]
[NO-PACKAGES]
[NO-EXTRA]"
                    ;; "book"
                    ("\\part{%s}" . "\\part*{%s}")
                    ("\\chapter{%s}" . "\\chapter*{%s}")
                    ("\\section{%s}" . "\\section*{%s}")
                    ("\\subsection{%s}" . "\\subsection*{%s}")
                    ("\\subsubsection{%s}" . "\\subsubsection*{%s}")))))
        (org-latex-default-class "nothing-at-all")
        (org-latex-with-hyperref nil)
        (org-latex-hyperref-template nil)
        (org-latex-prefer-user-labels t))
    (org-latex-export-as-latex)))

Is there a "clean", elispy way to do this?