That's actually what I do. I have a "RECORDING" track, trim what I don't want and move it into the appropriate track.You coud just record a new track, then trim off the bits you don't want.
Good points.Yes, all of these other Options do exist. I personally use a Pre-roll of 2 bars (Metronome) when Recording in Reaper with Recording set to "Auto-Punch" Time Selection. I do still use a Footswitch or my Transport's Record Button though. Sometimes it is actually just easier to start with the Footswitch with your Hands already in position, so I understand OPs request. Especially since Red Light Syndrome already exists, the less obstacles, the better!