WTH is with all this special Ubuntu versions?
If you want a low latency version then just offer a low-latency kernel that is a optional install and setup a group for realtime rights that a person can add a account to.
Does not seem a significant amount of difference from a normal server to justify a new variant.
Redhat is successful with working with companies that have special requirements like this. Figure out how they deal with it and see if it's worth copying.
I can do everything described above, and a lot more, just by taking a base Debian install and installing packages and reading the documentation provided by those packages.