I remember playing one such guitar in the eighties. Don't remember what it was, Hohner or something, but it was either 30 or 36. And about the only thing you could do on it was gliss. The shorter the string in relation to its diameter, the less it behaves like a string and the more it behaves like a rod. And if you've noticed, even by 21, your low E is pretty wonky. Complete and utter waste. If you really want the range, get a 7 or 8 string and put a 0.007 on there and tune it to G or even A if it'll take it.