Going ultralite and still camping out requires a certain bare minimum of gear to be comfortable and that gear equals VOLUME. Take a look at the photos at the bikepacking site -people have gear strapped all over the place, and most are carrying stuff on their backs besides!

Even the smallest tarp or bivy takes up some volume, even the lightest sleeping bag take up space when you go to pack it.

A person can't go civilized bike camping and get away from carrying

shelter
sleeping bag
sleeping pad
stove and cooking accoutrements ( you can always eat in restaurants or always eat cold food but that doesn't meet self sufficiency criteria)
spare set of clothing (socks and shorts at least)
warm clothing
shell clothing
warm hat
bike tools
water
personal effects


Sure, you can always stuff wadded newspaper in your clothes to stay warm at night and wrap yourself in a sheet of tyvek, but that's not touring, that's groveling.

Here's some photos of a couple of ultralite rigs I've gone with. And I'm currently dialing in the ultralite luggage hauling system in the garage right now on the travelers check - I'm adding light rear rack, getting rid of the bagman support, ditching the ortlieb handlebar bag for an Ostrich bag. I'm going to haul a couple of items on the rear rack, free up more space in the Carradice bag.

Should be stying, I'll be taking it on a weekend run this winter. keep everyone posted.

Travelerscheck in the Marin highlands this summer with carradice and ortlieb handlebar bag and a gallon of water. picture of inside of carradice bag with essentials -tarp, sleeping bag, ground cloth, etc. Inside of ostrich handlebar bag. Lower row shows a Trek 520 rigged with ultralite gear strapped to the bike in 2 stuffsacks and 2 backpack accessory pockets.