I'm just wondering if anybody is as insane as me to to apply their ultralight hiking principles to their carry-on luggage when they're flying on a plane?

I'm planning a trip to a couple countries in Europe next summer and wanted to see if I could fit everything I need into a carry-on size bag (which for domestic flights in Europe is a very small 21x13x8", albeit 22 pounds). This is a city to city type trip (i.e. no camping). Getting a LOT more luggage over there from the U.S. is easy size and weight wise (with many airlines still not charging extra for checked luggage), but those smaller country-to-country flights inside Europe are where it can cost 50 Euros (about $55) to check a single bag (and most flights are like $30...), and is why I wanted to try this out (plus I already had most of the stuff I needed so why not?)

With the appropriate size bag (I picked up an Osprey Porter 30-liter bag for cheap), I found it's a tight fit but completely doable. Used the same hiking clothes I always wear (which are light, compact, and stain/smell resistant: 3x shirts, 1x pants, 1x shorts, 2x socks and underwear, some backup sandals, froggtoggs and jacket; along with a quick dry towel and Coccon travelsheet for the hostels). Even used some of my larger bottles to repackage toiletries in. Computer, Kindle, 1-pound camera and all accessories, travel books (~2 pounds right there), USB battery pack, plug converters, sunglasses, water bottle, first aid kit - all picked out with ultralight in mind. Everything is coming out to 17 pounds!

...just wondering if anyone has done similar.