This is pretty great! One small critique - I'd add something over the sky, some graphical element, right now it looks empty and it's not too bad at this size but might be boring for a poster. I'd suggest clouds kind of echoing the shapes of hills near the shore, or the moon, or both, unless you can work a flying saucer in or something.I am also preparing for a local con and it's my first time after being a hermit for many many years and it's like there's a part of my brain that still believes it'll be good fun but most of me wants to cry from social anxiety