I'm wanting to make all our feeders easy fill from the ground. I've figured out timed feeders in another post. Now I'm figuring out our protein feeders.

All our protein feeders are in pens. They all are made with 55 gal barrels and are tripods. Some have boss buck spouts and some have academy game winner spouts. I'd like to keep the bottom of spouts about 38" from the ground. Barrels are 33" tall. That's a total of about 72" or 6'. What's the minimum length downspout we need for deer horns to not get hurt by the barrel. Minimum distance from bottom of barrel to bottom of spout? My barrels have flat bottoms with the funnels inside the barrel.