I understand your "coil replacement" comment, but what do you mean by "backup juice attachments"?
An experienced vaper will tell you that you need a backup for every part of your setup. Backup battery, backup juice attachment, backup juices. If any of those three are missing or non-functional, you CAN'T VAPE!
Believe me. Been there, done that. I let my all my batteries become drained so that I couldn't vape; I got a nicotine craving that would not stop so I drove to the store to buy a pack of cigarettes a month after my last one. Have only one tank? What happens when the coil decides to stop working? Do you have a replacement ready? What happens if you run out of juice? No vapor.
Vaping Rule Numero Uno - have backups for your backups !