I also created a custom template that added values to tinydns. I will need to test a bit more since my test machine doesn't have internet access., and the entries I added were private values and only one was active and routable. From what I've seen, just adding the custom info is all that is needed, my last test was without adding any host value. FWIW adding the custom template fragment isn't hard and if done this way it will remain after a normal upgrade.