I've been trying to dial in my HHSS system for proper level of insulation with outside temperatures... just completed a car camping trip over the weekend with an overnight low of 23F and had a VERY comfortable night.

Here's the setup: standard HHSS UC with OCF pad with space blanket on top. I added a 40F (900 down) top quilt to the UC below the OCF pad. I slept in a 15F Big Agnes Lost Ranger (650 down) sleeping bag with insulated air core pad inserted in the bag sleeve. My tarp was pulled low to the hammock with edges staked tight to the ground.

Great results! I stayed toasty warm with zero condensation in the hammock or UC.

A few weeks ago, I tried the standard HHSS UC with just the 40F TQ on top of me in the hammock during a 34F night - with marginal results. I bought the Big Agnes LR and pad 50% off at a local outfitter - using it inside the hammock and using my 40F TQ as a pseudo UQ really gave me a boost to handle the low 20s this past weekend. I feel I now have a setup to handle wide range of temps that I need.

Good Stuff!