No matter what size you are, you can wear a jacket with as many pockets as you want. Travel cheaper by looking like an vaudeville ex-army doomsday prepper with all your underwear stuffed into pockets of oversized cargo pants, three layers of socks and an entire towel as a toga shirt over your other shirts.
Pro-tip: If you have a greasy paper bag they'll think it's food and won't charge you for a carry-on.
Dude, I barely fit in the seats now with my phone in my pocket and you want me to carry a weeks worth of clothing and travel sized toiletries on my person?
I did this when I forgot a pair of shoes once. I felt so bad, but also so sly. The poor clerks probably have to deal with foot smell often, but it still just felt icky.
I'm always cold when flying, so I just layer up. Jeans, sweatpants, short sleeve, long sleeve, sweater, jacket, hat. Then, I put various items in my various pockets. Phone, earbuds, snack bars, bar of soap, small articles of clothing, maybe a tshirt in my jacket pocket, a shoe in each sweatpants pocket. The rest goes in my carry on, no luggage fees.