[embee]

Definitely need to consider carefully the mat issue. The cold comes up from the ground.

I use a thermarest mat, very good and packs quite small (I selected all my stuff on pack size for touring on the bike), there are somewhat cheaper "copies" now.

My bag is a down filled Vango 3 season which packs very small but as Dan says they don't come cheap (and also don't like getting wet, so care required). Even so I've woken up shivering while camping in France in July, don't underestimate how cold it can be at night in summer. The mummy hood type will help a lot keeping your head warm.