It’s been a while, but I have good news! It is okay to purchase the Kindle edition of Racing Pajamas on Amazon. I discovered that my Kindle Direct Publishing account, through which the RP eBook is available, is actually (and fortunately) a separate entity from my erstwhile Seller Account. I am grateful to have learned this (but it would have been extremely helpful if someone from the support team had told me that on the phone or had responded to my emails in the first place).
As mentioned in my post 2 months ago, the paperback edition of Racing Pajamas, as well as of Cartage, will not be available on Amazon. If you or someone you know would like to purchase either book, please contact me directly.