How to safely do a factory reset, lend my iPad, then restore it?
that should work fine.


Do your full backup
Go into General -> reset ->reset all content and settings


This COMPLETELY wipes the IOS device so your friend will set it up as if it were new.

When you get it back ask him to do the same thing first, in case they set a password. Sometimes if you have a PIN set you have to enter that to wipe it.

But your scenario should work fine