You need to pay speakeasy more money to make it work.
I've got a business account with them.
One if the features of a business account is DNS setup.
Without the DNS setup, you CANNOT get a reverse DNS to work since no matter what you say at register.com, if the ISP does not delegate the addresses it is not the authoratative name server, which means no one knows to go to it for the address.
Bottom line: You work by accident. No matter how well, it is still an accident.
But: You may be able to kludge it. Some more.
Change your system name to match the reverse DNS entry. Give it a shot.