I've been able to sleep down to 34* with a 1/2" CCF, 40* synthetic bag, and a lightweight fleece sleeping bag as additional liner. Those were all items I used ground-camping, I just elevated them in my DIY hammock for increased comfort!
I'm experimenting with under-insulation outside the hammock now only because I find carrying ccf & thermarest pads inconvenient- but for comfort, I truly don't need to go there. (Okay, wait- I'm a gear junkie too....)
ENJOY YOUR HAMMOCK without worrying that you HAVE to get other gear!