Thanks man! Great to meet another busker here <3
First of I dont think I ever played a nylon string guitar that could handle it... but maybe you play steelstring? If thats the case then a robust guitar, not to delicate or woody is required. If one could afford it i suspect that a carbon fibre guitar like a "rainsong" guitar would work very well. I play a Takamine, a discontiniued model, but very similar to the EF341SC and its been with me for 10 years and still going strong...
For oneself its key to dress warmer all over the body then what you would find normal... to the point where you are warm instead of not feeling cold... just below the point where you sweat outdoors ;) That way you have warm blood circulating your fingers through out your shift! Its not gonna go hand in hand with a cool appearance though :P
also dress the hands as much as possible... the right hand (if you are righthandeed that is) only needs the tips uncoverd and the left hand can pretty much handle only uncovering the pointing finger (dont know the correct word, english is a second language, but the finger closest to the thumb) for your barre chords and the other fingers can just have the tip uncovered! Woolen wristwarmers up to the knuckles if needed... and if you are really pushing below water freezing point then there are some other opptions im glad to discuss if its even an issue where you live!
haha wow, thank you for such a precise breakdown, I'm living in NYC and its pretty cold in the winter, coming from the UK its colder than I am used too which a lot of people don't realise. Thankfully spring is just raising it's glorious sprouts!