Bikepacking - a viable alternative to racks & panniers

Can't say I've ever slept on a camping mat that was comfy :/

Closest I've ever come was one that was basically a rolled up mattress.

For bike camping?
Probably doesn't exist.
Evazote is pretty cheap and can be comfish in the thicker ranges, but it's bulky and not ultra light.

Exped Lite has been fine for me.

In your list, I'd say 'tough' is it's lowest score - it's just a bag of air after all, so check the ground and protect it underneath if on sharp or thorny ground.

second hand neo air

Uh? Thermarest Ultralite? standard no?