It's not really uncommon to use classical guitars for songs that aren't classical lol. It would actually make more sense to use since nylon strings aren't as harsh as steel strings. Classical guitars also give a nicer tone for jazz as well.
to make things a little bit easier, i suggest playing it in daeac#e, and then go capo 6. You pretty much did what TTNG did for 26 is dancier than 4, but i learned that exact song but in that^ tuning on capo 6. exact same sound, just more room to play.
I have a very similar tuning, CEGBDF, based on a Cmaj11. This works well not only as a beautiful tuning but when you need it it can become really heavy.
how long does it take to get this proficient at guitar? I've been playing for 3 months and I know thats not near enough time, but this just seems so far out of reach.
I'm no expert, and now I certainly don't play like he does, but i think after 2,5 years or at least 3 of putting in work this is definitely very achievable I do believe it can be done even at that time if you, while still having fun learning and playing guitar, always expend your boundaries a little bit further. It is really important for me And, I know you didn't ask for personal experience but after playing for more than seven years, the last two years when I was learning and playing something I actually love and expanding my boundaries (I was playing classical music in music school before that) counted so much i can't even compare my five years in music school to that Sorry for the long message but all I'm saying is if you keep your focus while also having fun i genuinely believe that you will be amazed at what you achieved in not a long time