Oh dear.
To make a very long story (feel free to search the forums, use search term: "kustom kettle") eGO had a custom map server for almost an entire year, and it closed around this time actually, one year ago. The server, throughout that entire period of time, was not anywhere near as successful as the other 24/7 servers. In fact, when comparing the two, the custom server was a complete failure.
Thus, I would venture to say that any further attempts at a custom map server are unlikely. And don't take this the wrong way, I personally.. would love one. I was actually the system administrator for both the eGO custom map server, and the eGO orange map server. But... I'm also realistic. As much as I would like it, the community here clearly doesn't have the numbers to support it.
Now, before dozens of you again come and say "but I would play!", I encourage you to look at the DoD stats page. You will see that the vast majority of the top players (just looking at page 1) spend nearly 100% of their playing time on one, or two maps. That's it. And so the problem we faced with the custom server was that people refused to populate it. Usually with phrases like "but I'm good at Donner, I don't want to learn a whole new map" ... over and over again.
Sad, but reality.