I would do a clip that leaves hair on the upper portion of the neck, all of the legs, and the head, like a Trace Clip. Here's a web site showing the different clips. Use a permanent marker to draw out your clip pattern before you get started.
How Much To Clip
If you do a Hunter or Full clip, I would go with a 1,200 denier medium weight waterproof turnout blanket. Get two more blankets to use to layer, one fleece type layer/cooler, and a mid-weight stable blanket. Use just the medium weight for weather above or around freezing, with the fleece layer for below freezing, and with the stable blanket for below 0 temps.
Does that make sense?
If you only do the trace clip, you won't need to full blanket like that, but the horse will cool off quicker when worked. You would only need the medium wieght turnout blanket. However, it will take some time for him to dry if you ride hard. You might want to do a blanket clip or hunter clip if you plan on working him hard regularly.