Unfortunately you can't have 2 SIM cards tied to the same number - otherwise I'd do something similar to your idea with my own LG G3 and Samsung S4. Texts I use SMS Backup and Restore (
https://play.google.com/store/apps/details?id=com.riteshsahu.SMSBackupRestore&hl=en) along with the Network Add-On from the same developer to synch my SMS between devices. You can even set it to perform a backup at regular intervals if you want. Call logs I don't worry about and everything else is cloud-based, meaning if it's not automatically synched, it's easy to get to the stuff I need.
To make things even easier, I tend to leave one device at home (where it's connected to WiFi) so it's usually a matter of shutting both devices, swapping the SIM, turn both on, and confirm I have everything synced, and go - usually about 5 minutes or so.