Anybody have any tips on getting either to work?
While having current packages can certainly be a benefit – it’s also a drawback 
Running a server is typically about stability; it’s difficult to run a distro with such new packages and also maintain that stability.
Fedora is also known for it’s short life-cycle. At most, it’ll be supported for a year before you’ll need to upgrade.
Most people tend not to like those factors on a server 
So then, how can you get a server distro like CentOS to handle the dependencies for your web apps? Well, that can be tricky too 
You can start by taking a peek at Virtualmin’s Bleeding Edge repo:
https://www.virtualmin.com/documentation/id%2Cvirtualmin_bleeding_edge_packages
Beyond that, if there’s still apps you need, you’d need to either find them from another repo, or take a source RPM of a newer version, and compile that on your distro.
The catch is, though, that Virtualmin GPL is not supported on Fedora – and even Virtualmin Pro only has Fedora 10 support thus far. And that’s because Fedora is considered to be a bad server distro for the reasons mentioned above – the short life cycle, and bleeding edge packages.
That’s not to say you can’t get Virtualmin to work at all on a Fedora-based system, but the installer won’t be able to configure everything, and you won’t be able to use the Virtualmin RPM repository.
You can check out this manual installation guide for some ideas:
https://www.virtualmin.com/documentation/installation/manual
-Eric