1. I have spent 6 weeks self-supported this summer, crossing an area where re-supplying was challenging at best. Everything did fit in 2x12.5L panniers + my tent & Ursack (for food items) attached to the rear rack (see pictures below)
2. I would suggest that you try to fit everything inside your two panniers while securing the tent to the rear rack. If it rains when you break camp, you don't want your tent to be packed with your gear anyway.
3. Keep in mind that you could start with empty panniers and purchase what you need as you go, as long as you do not start on a Sunday
(when most French stores are closed).
4. You plan to carry a LOT of clothing. In essence, a base layer + 2 mid layers + whatever is needed to keep you warm + a shell is enough. Wash when you set camp and it'll likely be (reasonably) dry the next morning
5. No need to carry propane spare(s). When you run out, eat something that doesn't need cooking (plenty of options) or find a nice restaurant. And the nearest Decathlon
6. No need for a full tape roll. Many backpackers will wrap a meter or so on a tent pole. (or bike frame)
7. you can probably get by with a smaller bath towel (I use an ultralight face-size towel -- similar to swimmers wipes) and mechanic rags can be replaced by paper towels that you find at a gas station
8. I see no electronics. No phone/GPS/battery pack/charging cables?
9. I'd suggest a larger pump.
Cooking includes a 700ml kettle, 600 & 450 ml double-walled mugs, folding fork and spoon, ESBIT stove (a marvel if you ask me), an electronic lighter and a few days' supply of fuel tablets.
Hygiene includes a small UL towel, toothbrush + paste, soap bar in a pertex pouch, razor & blades.
Tops includes 1 short sleeve T, 2 long sleeve Ts (1 thermal, 1 lightweight) and 1 3D hoodie (heavier thermal) (minus what I wore that day)
Bottoms includes 1 pair of shorts, 1 pair of running tights, 1 yoga pant, 2 underwear, 1 pair of socks (minus what I wore that day)
Rain gear includes OR Helium jacket and pants, Hydroskin neoprene socks (excellent) & RAIDLight mitts (well....). I also carried an Houdini Air windbreaker.
Misc supplies includes oil, grease, a short lenght of chain (which I've used to remove my cassette), a fiberFix emergency spoke, etc
Electronics includes 2x Petzl Bindi head lights (fantastic), 2x 10 000 mAh battery packs, 2 USB-C cables, 2 USB-C> microUSB adapters, 2 USB-C > Garmin shortened cables + 1 20W PD wall charger. Phone, Kindle and inReach in handlebar bag.