Na, I've slept out in summer in the hammock in just a sleeping bag and been fine. Wasn't a particularly hot night but it wasn't cold/raining either so take that as a very small sample size. Testing is best ting, even if you just go out for an hour and read your bike one night, you'll get a good idea. But imo don't both taking it because you can always layer up inside your sleeping bag if you're cold.
Na, I've slept out in summer in the hammock in just a sleeping bag and been fine. Wasn't a particularly hot night but it wasn't cold/raining either so take that as a very small sample size. Testing is best ting, even if you just go out for an hour and read your bike one night, you'll get a good idea. But imo don't both taking it because you can always layer up inside your sleeping bag if you're cold.