My high school English teacher always nagged us about not splitting our infinitives, but this would just sound wrong if I said "as not to drop anything." Is this an acceptable exception?
The most famous English split infinitive caused a grammatical stir upon its introduction, which the writers wisely ignored.
If you've a high school English teacher who nagged about split infinitives that says a lot more about the quality of high school education, than it does about English.
It's certainly worth knowing as part of the history of the language that there was a brief period in which a strange cult of English intellectuals, having abandoned Latin for the vernacular in their bible and prayerbook, were caught up in a spirit of longing for it, and tried to insert it into their English grammar book.
Saying you shouldn't split the infinitive in English is like saying you shouldn't give oats to a horse, because you never do to a car.
But outside of that bit of historical interest, what business does an English teacher have teaching such nonsense?
It's also worth considering with composition that when there is a splitting and non-splitting form available, that the non-splitting may well sound better, but that's not because not splitting is inherently better, and there are as many cases where the opposite is true.
In this case, I find it hard to decide on a preference: one has the idiomatic "so as to" while the other applies the negative to the whole of the infinitive which just personally strikes me as slightly preferable (in a very subjective way, there's no real way to justify that preference in terms of grammar).
The more unusual matter would be saying "as to" about an intent, generally "so as to" explains an intent, and "as to" meaning with regard to:
Dropping "so" is more colloquial.