You aren't the first dev who I have heard of issues with file size uploading with Itch. Hopefully at some point they upgrade things on their end or do whatever it is they have to do in order to solve this for future games. If you are able to sell the full game on Itch I will happily buy it full price as soon as it is up. I despise Patreon for a variety of reasons although I understand why people flock to it for it's widespread popularity and simplification for many things.