I think both of your options are valid and can do the job.
However, for option 1, when you are switching config from non provisioned chassis to pre-provisioned chassis along with role changes, VCCPD will restart and ask you to reloing in the devices.
By chance if the preprovisioning is not formed correctly, you might need to troubleshooting.
For option 2, even if you are doing the changes more time, you are having a complete control of the process. Hence, whenever you are switching the members, your transit traffic should remain least impacted only the management traffic may have a slight glitch during step 3. Otherwise it looks good.
I beleive you do not need to restart as per the documents available as it is a non distruptive changes.
you might want to use "request virtual-chassis reactivate" command in case of re election of master and backup master.
HTH