Hi fellow Ohioan! (and I live in NE Ohio, on the snow belt!!) ;) My horse is trace clipped like the image you showed in your original post. And the Ohio weather (of course) has been nutty lately!! 20's at night, and then 40's today, and 55 tomorrow, back down to 30's on Weds and snow!!! GEESH!
Anyway, I've been bouncing back and forth between a light weight and medium weight since the temps starting dropping to highs during the day only in the 40's. Generally if it's in the 50's I just use a waterproof rain sheet for turnout (although my mare destroyed hers the other day so I'll be using her light weight until I get it fixed! lol) Once the highs are in the 30's (like Weds) I use her medium weight, and I actually don't own a heavy weight blanket, I just use a wool blanket as a layer underneath her medium weight if it gets into the teens at all.
I always monitor her temp, you know, the old stick your hand under the blanket up against her back/side/chest trick! ;) If she feels too warm or is sweating at all, I drop the blanket weight down a notch. If she feels cool to the touch, put a slightly heavier one on. I can't always get it right since I board and work full time, so I have to blanket her at night when I'm at the barn, then can't make any changes until I'm off work the next night, so I rely on the weather report a LOT! But basically as long as you get it close to right, I'm sure your horse will be fine, they're pretty hardy animals! ;)
As long as you're not over blanketing and making your horse feel like he's dripping wet and in a sauna...or the other extreme -- making your clipped horse who has half of his natural coat protection gone stand around in the below freezing wind chills without a blanket! I think he'll be fine and ready for this horrible Ohio winter everyone's been talking about already!
"The times when you have seen only one set of footprints in the sand, is when I carried you..."