Yep this is exactly what I did. It’s a feature I was unsure is available on the iPad, or do people without a computer forego this ability?
I did a search for backing up iPhone to iPad, and it doesn't appear to be possible. I mean, you can send selective stuff wirelessly to your devices, but not a full backup. And yes, if you don't have a Mac or PC, the only option you have is the cloud. Would be really nice imo if Apple would make it possible to backup your phone to the iPad. If there is a way, I just haven't found it yet.