I just came back from a week long trip in the Everglades. I used a pad under me, in between the 2 layers of my WBBB, and a 40* top quilt from UnderGround Quilts. Worked very well for me, and I spent a couple of nights without the TQ altogether.
I am a warm sleeper, so your needs might be more. I would think a base layer added on would solve any problems.