large list

I can think of 2 methods that would not be too difficult. IF the "longest line" is available to you, calculate the font size you need to make it fit in a single page width and then pass that value as a parameter to your function.

If that is not known ahead of time, then you could output as you are now, creating wider pages. Then use "CapturePage/DrawCapturedPage" and draw those pages onto pages of the desired size. This will shrink the text by the ratio of the original page to the drawn page, however, and the result may not be easily read if the factors are large, or if the x/y ratios differ signficantly (you may end up with very thin, tall text)