Ugh, nights like that seem endless.

Comfort and insulation (R value) can be considered together or individually. If you have a mattress/pad that is comfortable in milder temperatures, then you can simply tote a foam pad to add to your mattress for the needed extra insulation. Or, look for something with an R value of 4 or so, and use that instead. The pad type is personal preference and will generally be a foam self-inflator or an air mattress with some kind of insulation scheme, usually either reflective baffles or fiber insulation. My favorites have been the Thermarest Neoairs and Sea to Summit Ulitrlite Insulated. They pack much smaller than foam.

Hammocking can be super comfortable but insulation for winter is its own topic. Suspended in air you're losing convective heat on all sides and many hammocks compress the sleeping bag on the sides, meaning wraparound insulation of some kind and maybe substituting a quilt for sleeping bag.

Good luck!