Well I can't help you with the canvas size problem bc I've never used procreate, but unless you reaaally want to see the whole episode in one canvas I recommend just drawing it onto smaller (like cut your episode into three our four canvases depending how long it is) parts and then using croppy. https://knicknic.github.io/croppy/
it can seamlessly cut your episodes into smaller images fit for webtoon or tapas, then you can just save your pictures (no need to download the zip file) individually once it's done and upload all the pictures to tapas/webtoon to make a seamless, long episode ^^ I hope this helps~