My general question is as such: If I use a 30°F (-1°C) under quilt with my hammock, would I be fine using a 50°F (10°C; or higher) sleeping bag as a "top quit" during 30°F (-1°C) winter nights? My thinking is that since the under quilt is the primary insulator the "top quilt" wouldn't need to provide as much insulation.
I mainly camp in Louisiana and Mississippi so the temperature and humidity tend to stay higher during the cold months but can dip into the high teens (-10°C–-6°C) on extreme nights but mostly stay in the mid to 30's °F (couple of °C above zero). I would like to continue to cut weight by purchasing a cooler (warmer weather) sleeping bag and use it as a "top quilt" with my under quilt as my primary insulator.
I tend to sleep pretty cold from past experiences with ground camping during the winter months. I currently own a 20°F (-7°C) sleeping bag that I've used in my hammock without any under pad/quilt on a 50°F (10°C) night and slept great.
To make the answer more "yes/no" possible. I basically want to know if using an under quilt will allow me to skip the top quilt.