You can do it manually by using the apply master page command from the panel flyout and typing in all the even numbers, or I'm sure it can be scripted. Someone probably already has.
That said, why not use a two-page master spread and change the left page to look the way you want? This will work with a facing pages document.
Currently I'm using 1 page spreads in the document because I wanted it to be easier to read in PDF format, but when I printed the pages double sided, the page numbering is running into the margins when bound on the even numbered pages.
There was probably a way to have a two page spread export out in PDF and only show one page at a time, but I had no idea how to do it, so this seemed simplest.
Is there a way to convert the document over into a two page spread now that I've gotten this far?
Sure. Go back to Document setup and check the Facing Pages box, then go the master page, select Master Page Options, and change the number of pages to 2. Add what you need to the master.
When you export, select PDF (Print) rather than PDF (Interactive), and as long as you don't check the Spreads box you'll get single pages. If you actually have interactive content that is not preserved in a Print PDF, come back and we'll tell yo how to export PDF (interactive) as singles instead of spreads.