Conflict between CSI volumes and raw_exec prestart and poststop tasks

I need to build a NixOS system with a pre_exec prestart task, then delete it with a poststop task. Which means the job group must contain 2 raw_exec tasks and 1 systemd-nspawn task. But raw_exec doesn’t support CSI volumes and I can’t tell nomad to only apply the volume to the main application task. And I can’t split up the group because I need those prestart and poststop tasks. How can I resolve this situation?