Should be possible, just use conventional disposable instead of named one. For that you will need to configure everything in the disposable template.
It has its own disadvantage. Since all disposables inherit the same template, you will need to either provide VPN configurations after the start of a disposable, or use the same configuration for all of them, which kind of kills the purpose.
There may be a way to automate VPN configs using salt, but I’m not sure. Salt is broken in fedoras right now, so if you want to experiment with this use another distribution.