Actually, a DC covers more squares than DL or DR in zonal marking. You say you don't want to go illegal due to suspension or injury, but this can be avoided by playing wide players elsewhere, for example in the butterfly. However, you always run the risk of going illegal if you play with just 3 defenders.
I, for one, am willing to take that risk, though. My base formation is 3-2-2-2-1, which parts are wide and narrow depends on the opponent I'm facing.