Any way to dynamically create copies of worlds at runtime?

[Schwertspize]

That means basically shutdown or start a second instance.... That means the best way is starting another instance from the same config/server dir, make world readonly and supply port as command line argument.

[DrMasik]

I'm use another solution in my Sky wars plugin.
I'm save data of the map into DB. On load it is in border of map. Save current position of loaded map and load new map after 16*visible chunks. When game is over - loaded map (area) cleaned. If all maps are cleaned - next loaded map (area) position - clean.
You can try it on m-c.link:25567 in white building near spawn. Server uptime 98%
It's use russian language. In future - multi language