I'd take the poncho/tarp plus bivy just to see what it can handle. I am novice with regard to tarp camping, and I am a glutton for real-world practice. I would probably take the gear list that is in my profile, but (maybe) add swap out my torso pad for a 3/4 Ridgerest and my Marmot Hydrogen.
Recently, I was going to take a trip up to some of the state parks up there, and was having a shelter quibble. The options were between my MK1, CatTarp 2 /w double bivy and my DoubleRainbow. Before I got a good look at trail conditions, I was considering taking all of them in the car and making a trailhead decision as to what to pack in. (The trip was canceled, btw, because of a severe ice storm.)
Dan makes a great point about weather. Although there are some exposed cliffs on the SHT, there are many, many sections where one is just woods walking with little exposure to sunlight. Although the trees will not bud leaves for another month, you are still looking at limited sunlight potential. It can be messy up there with lake breezes, windy conditions and mist. Hypothermia is a real possibility.
All that said, I'd still be inclined to push the system. Maybe boost pad warmth?