Haha I do the same thing don't worry! Ironically I have a 64gb 6 and I try to keep it as free as possible which makes no sense but it's my OCD. I can't justify getting a bigger iPad as I never really keep music or games in it. I just use it for surfing, reading, shopping and watching a film or two when travelling. I always delete the films after I've seen them so that isn't an issue. I just think it's really poor the big guns get away without implementing a proper garbage collection to clear the temp cache.
One thing I will never do again is buy a wifi only iPad. I had no idea that only the 3/4G iPads have GPS. I'd love to have my TomTom app on my mini and use all the other features within apps from having GPS.