If I were trying to do imposing, then yes this seems like a solution, but I am not trying to do imposing--I'm not a publisher, nor a printer.
Moreover, I'm not looking to maintain the individual pages; rather I am looking to destroy the page construct.
I want to replace the 8.5" x 11" page with a page 8.5" x 22" so that I can fit twice as much stuff and even more if I make the page longer.
Let's say I want to create a jpg from the pdf file--I want to create ONE jpg from what were two pages of a pdf.
and on the related question...How do I create a blank pdf of arbitrary size?
Something to try.
Open a test copy of your two page, 8.5 x 11 each, PDF.
Open the Crop Tool dialog.
Tools > Advanced Editing > Crop Tool
With the cursor anywhere in page, double click.
At the bottom of the Crop Pages dialog you will see the Change Page Size pane.
Tick the 'Custom' selection.
Enter 8.5 for the value of Width and 22 for the value of Height.
In the adjacent Page Range pane, select 'All' of 'From: --- ' and 'To: ---'
Note the 'Apply to:' choice as well.
Once configured, click OK.
Your Page Range selection becomes 8.5 x 22.
Reduce page magnification and, perhaps select a scroll page view.
Use the TouchUp Object tool to marquee a graphics object and nudge/move it about on a page or between pages.
About File > Create PDF > From Blank Page.
The page size for this is determined by the values used in the "New Document" Category of Acrobat's Preferences.
The page size choices are limited to those in the drop-down menu.
An alternative for creating a custom page size PDF via MS Word is discussed in this thread: