I use my Kindle Paperwhite completely offline. I factory reset it and haven't connected it to WiFi since and just side load what I need(I did have to strip the DRM from my Kindle books to side load them on the unregistered device). I never really used the online features when it was registered previously and kept it in airplane mode to help with batter life. Another bonus is that if a freshly reset Kindle never connects to the internet, you never get the ads.