Share printer over VPN

Question

I have a customer who just recently bought two Cisco ASA 5505's from us. He will be buying several more for each of his business offices, but for now we have one set up at his main office and one at his house. Not only is this for testing purposes, but he also wants to be able to print from his office to the printer at his house. I have successfully set up a site-to-site VPN connection between the two locations and can successfully ping the IP addresses on the other side of the tunnel no matter which side I am on. Here's the problem I'm having: There is a Windows Server 2012 Essentials server providing DNS to his network at his office location. At his house there is a printer connected via USB to one of his computers and shared over the network. From his house I can access the shared files on the server by typing serverhostname.domainname.local into Windows Explorer. However, since he doesn't have any device providing DNS at his house, I'm unsure of how to add the printer to the computers at his office. I'm trying to avoid having to add the computer at his house to the domain of his office. To make it more clear what I'm trying to do, here is a quick diagram:

Canon USB Printer - Windows 7 Professional Computer - Cisco ASA 5505 (residence) - VPN Tunnel - Cisco ASA 5505 (office) - Server

For now I just need the server to be able to print to the printer at his house.

I've tried adding the printer with the IP address, but when I do that nothing prints. I don't get any errors or jobs stuck in the queue or anything, it simply doesn't print. I have this same problem when trying to add a printer by IP address on a local network. Even so, I'd rather print to a hostname anyway in case the IP address of the computer changes and I'd rather not make it static. But I will do so if that's the only solution.

Is there a way to make the Windows DNS server at his office keep track of the host names at his residence over the VPN without adding the computers at his residence to the Windows domain? Is there another way to add the printer without having to do this?