Using just the equipment you now have (pad, bag, clothes), my opinion is that you could make it through the night at 35* in a hammock (with a tarp). But, IMO, you will make it through much warmer in a Clark. The weathersheild will increase the inside temp measurably and, if needed, the pockets can be stuffed with clothes, leaves, etc.
You are right about the weight - there is not much, if anythiing, to be gained in weight savings by hanging vs. tenting so any equipment you have to add over what you already have tips the scales even more. With the Clark, when it is above 55* I don't carry any extra bottom insulation.
"...With saddle and pack, by paddle and track, let's go to the land of beyond."