First off, I don't believe there even is a clientCmd for F5. Doing so would require a clientside add-on, which is not ideal for anything. Second, if it did work, all it would take is one person to simply press F5 to ruin it.
This is for a rather simple game mode that I'm working on. A short distance will work for most of the players, but for one of the players, I would prefer a completely hidden name.