Nice! I did
a similar trip last year and am gonna go to Seattle again this year. Bringing a friend with me (also on a 250), but we'll be going in July, hoping for better weather.
I would say you are for sure going to get wet, so be prepared for it. It's not too bad if you're prepared. I wasn't really. Also, getting back in two days along the coast is a stretch.
I did it on Pirelli Sport Demons, your tires are fine.