I got an email from someone at BackPage saying that if you pay for an advert on Cracker it will appear on Backpage. So, I bought some credits on the Cracker site with my Credit Card, and posted an advert. Bought a couple of things like relisting and sponsored. Very cheap, really. Sure enough, there I am on Backpage!
The Bitcoin option for payment is very prominently placed but to pay by credit card or your account credits is very simple. However, I didn't post it on Backpage - I posted it on Cracker and it appeared on Backpage.
I don't know if anybody ever finds Cracker but at the very worst I'm on two sites for the price of one.