Any chance to see --backup-dir supported by delete too?
Alternatively, can I assume that: rclone copyto remote:file/to/delete remote:<backup-dir>/file/to/delete<suffix> followed by: rclone delete remote:file/to/delete would have the same effect?
rclone copyto remote:file/to/delete remote:<backup-dir>/file/to/delete<suffix>
rclone delete remote:file/to/delete
This would be quite easy however you can just recast your command as a move
rclone moveto remote:file/to/delete remote:<backup-dir>/file/to/delete<suffix>
would be more like it.