Hello and welcome to iMore! I know that some people use their iCloud Mail but I do not. I have "Mail" toggled off. To do this, go to go to settings > tap your name > tap iCloud > scroll down to Mail and tap the toggle to off (it will be white).
I'm not sure if this is what you're looking for, but here's how I back-up my iPad. I have it set up to automatic backup, so when my iPad is connected to Wi-Fi, and plugged in and the screen is locked, it will back up.
I can also start a back up manually. I go to Connect to Wi-Fi > go to settings > tap your name > tap iCloud > tap iCloud BackUp > tap Back Up Now
If you have further questions, check this out:
Directions for backing up your iPad