You can always start out with a narrow trace clip and work it a bit wider as you work your horse to see if it is enough. If you know where your horse begins to sweat or sweats the most this will give you an idea of what type of clip to do.
I used a modified bib clip on mine and it worked great. clip half the neck (lower) and a then clip the chest and finish off by clipping a little around the shoulder and between the legs to almost the girth. I clipped the girth area once and found that my horse got some rubs there, so I stopped clipping the girth area.
My current mount is a grey and I body clip him early, then change to an irish clip then to a bib clip as the season moves along. I do this because he loves to get dirty and needs to be bathed before every hunt. As the season progresses he is in a blanket so the main body is not exposed to the dirt and grime, so I only clip the parts that will need to be bathed regularly.