What should I take?

You said you are sleeping wild, so whatever you sleep under is on the bike. A bivvy is lightest and a tarp is the compromise; a tent is the one that works when it rains for three days.

You said nights drop to 15 °C. Ask for the comfort rating, not the limit rating — the limit figure is a survival number and you will not sleep at it. Five degrees of headroom covers a forecast that comes in wrong.

You said nights drop to 2 °C. Ask for the comfort rating, not the limit rating — the limit figure is a survival number and you will not sleep at it. Five degrees of headroom covers a forecast that comes in wrong.

At 2 °C the ground takes more heat out of you than the air does. The mat's R-value matters more than the bag's rating at this point, and it is the mistake people make first.

You expect rain and you are pitching on ground you have not chosen in advance. This is the cheapest thing that stops water coming up from underneath.

You said rain is likely. Wet plus moving air is how riders get cold in summer, and it is much harder to recover from than to prevent.

You said 70 km between water. That is the stretch that decides how many bottles you need, not the total distance.

You said you want to cook. Fuel is the part people underestimate — carry for the gap between shops, not for the night.

A stove without a pot is dead weight, and a lighter is the thing that gets forgotten.