Echoing a lot of what’s been said - pack the minimum to deal with the conditions you’re likely to meet via layers (1 pair shorts + legwarmers, rather than a pair of shorts and a pair of tights), and do laundry a lot.
If cycling is the main focus of your trip, I’d personally recommend to pack your saddle just in case. I’ve had rental bikes with saddles that were just fine, and ones where I made it about 50 feet out of the rental shop before turning around to have them put my saddle on. I think it’s worth the extra bulk/weight to not risk having your trip ruined by a saddle sore on day 1. But all bums are different, so YMMV.
Along with the “pack light and do laundry” I’ll add the advice to start your laundry the moment you get back to your hotel room. Whether by putting it in to soak while you go find a snack, or taking it into the shower with you, or whatever else - the longer you delay starting the laundry, the harder it gets to do it, at least in my experience!
And then most importantly - have an amazing trip!