I fail to understand your hesitancy to putting your FAA registration number on the outer surface of the drone. What possible reason (besides not actually having a registration number) could there be to hide it in the battery compartment?
The reason the FAA wants it on the outside of the drone is so that law enforcement can quickly assess if a drone pilot is flying with an unregistered drone (or an unregistered pilot). Good idea, because the people skirting the law are only making drone life more difficult for everyone else. We are getting these rules because of people that don't have common sense and shouldn't own a drone in the first place.
I think having the FAA number on the drone looks kinda cool.
I am going to leave a comment at your link, however. To tell the FAA that it's a great idea and that there should be a minimum size for the characters stipulated in the rule.
Mark