These are the settings that I used.
If you insert pages from the job after each page then you should have two copies of all pages in the body of the booklet. That should be what you need for resizing.
I've been asked a number of times whether it is possible to automatically unimpose booklets that have been laid out in reader's spreads.
The short answer is that this is certainly possible and furthermore it is possible to build a simple workflow that will unimpose reader's spreads for booklets of any size. This is what that workflow looks like:
This example covers the typical reader's spread imposition in which the first and last page are unimposed but the rest of the booklet has pages side by side in sequential order
Note: The colored boxes are not exactly centered. I am using the file as I received it from the customer.
The first step in the workflow is to split the booklet into imposed and unimposed components. In this specific case, we separate the front cover and the back cover from the body of the booklet
Once that's done the PDF in the center path in the workflow will only contain imposed pages
The center path in the workflow will duplicate all pages in the document and insert the duplicates immediately after the page that was duplicated. The result is the following
Once the pages are duplicated, they should be cropped using the following Resize settings
This will crop pages to 50% of their original width while aligning to the binding edge. As such, the left half of the odd pages and the right half of the even pages will remain visible in the resizes PDF
The last step is to merge the workflow branches into a join component. The files will be joined based on the split sequence. As such, the final file will contain the front cover, the body and the back cover as a 1up PDF. This file can then be imposed or otherwise processed through the workflow.