Perhaps something like this:
hzpLogicRTLLastPageListSelect.aia (61.2 KB)
I used a listpicker to display the pages that "can" be picked:
then afterPicking, assigned the desired pages to each of the vertical arrangements, then scrolling to the "first" pager component.
Note: this could be onerous once you have hundreds of pages, so your textbox approach for setting the page number may be better, with a check that it can be picked.