I'm an outdoor enthusiast, do a good bit of hiking, trail running, camping etc...
I once had a friend who is into ultra-light camping tell me how "lame" I was for using a rollaboard at work and looking like every other stooge. She said I should be using my trekking backpack. I could not convince her otherwise.

Point is, your outdoor hobbies are cool, but they are separate from your job as an airline pilot. You don't have to buy the exact same bag as everyone else, but you do need to pack clean clothes and all the associated amenities to keep up your appearance and hygiene. You can minimize these if you never plan on leaving your hotel room.

As for me, flip flops in the summer and Vans slip ons in the winter save space. Also, having black work shoes that actually look good with jeans help. For a four day I pack four white under shirts, 4 dress socks, 4 briefs. The rest is whatever you need.