What an amazing idea! I'm working on my first cross-promo right now with a new Webtoons friend and it's been a blast, I have been wanting to do more of those but wasn't sure how to approach the subject to authors!
I'd be interested in promoting 3 comics in banner form on my next update (Monday), ones that are related to my genre and that I genuinely think are great. Our comic is fantasy/mystery and we have around 1.3k subs. Anyone interested?