It's not just in your head. You don't need all that junk on your bike. You need lights, a decent size rear bag, a top tube bag, and a good pump. That's it. Fender mounts aren't even necessary anymore. You can get full fenders that hang on the skewers. A hub is a good option, but can use the same rim and spokes that your regular fast wheels use. I've done all my brevets and other long distance rides on 23mm tires on a carbon bike. If your carbon frame is still comfortable at the end of a double, it'll be fine on a brevet.
For rear bags, the large Ortlieb saddle bag or the Arkel Randonneur Rack and Bag are plenty. Plus your jersey pockets for nibbles and clothing bits and brevet card.
For me, brevet comfort involves getting my legs and butt off the bike ASAP and having the least wear and tear on these items between start and finish. Plus fast and easy is way more fun.
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