We had a pretty busy steel league which shot 99% of the time on a 50' indoor range, so 15 yards was the minimum we could shoot.
Jacketed bullets of any type were trouble. The hardest hits I took were from JHP jackets that had peeled off and came back 180 degrees to hit me in the peanut gallery. I'd wear a Levi jacket until it was my turn to shoot, and I wasn't above hiding behind a sheet of cardboard. I was taping a training class one time from about 50 yards away and I could hear bullet fragments landing in the dry grass around me.
Keep the plated angled down (a few degree will do), which will drive most of the fragments down. Don't set up your plate rack directly under the light fixtures. Good quality steel won't crater, and you'll get less bullet pieces coming back. Replace your poppers when they get bowed.
Some other notes. Consider painting your steel between runs. Orchard Supply has cheap $1.99 a can house brand spray paint. That'll allow you to see where you're hitting, with a quick touch-up before the next shooter comes to the line.
A fun drill, if you have two plate racks, is to "race". Two shooters start simultaneously, and the first guy to clear the plates wins. It helps to have a judge stand behind each shooter and hold his arm up as soon as his shooter clears his rack.