iPad Air flash storage

[Husq250]

Hello. I have a question or maybe just a thought about the iPad airs flash storage and IOS 8. I've been running the iPad through my iPhones hotspot and that's been working really well for me. Yesterday i went into settings and had a look at remaining storage (for other reasons) and it showed 1.9 G left. Went about the morning, remembered the IOS 8 was dropping and was hopeful i could update to the latest IOS 7 before it's to late. I've been displeased with some of the OS updates in the past in how the devices run with them and i have decided to remain on 7 where I'm happy with it. Checked- too late. IOS 8 is there. I know that in the past IOS forces a download and waits for us to install it and I did not want this eating up storage because I have no plans to go to 8. I ALSO checked my flash storage since "checking for update" and it had blown down to 1.4 G in just a handful of minutes! That means since I checked for the software update it was already trying to download it. I quickly shut off wifi and rechecked. Sure enough I'm back to 1.9 G. So now I'm using the iPad with my iPhones hotspot through bluetooth because IOS updates require a wifi connection to download. Dang, I'm going to have to use my bluetooth hotspot unless i fill the iPad with something that does not leave enough space for the new IOS to auto download wont I?

Thanks for listening. Any advice will be listened to.