What's a monaco?
Well...
These looked like sleeveless tops which zip up at the front.
Yes, that would be them. Imagine a trisuit as separate top & bottom halves. The top is a monaco. More information on Schmunks' pirate kit thread.
The spring ballbuster doesn't usually fill, but there'll be a closing date for entries and you can't enter on the day. As AH has hinted, I usually do it as a pre-VLM race.