How do you race your own ghost when doing hot laps?
Go into Rivals, highlight the track you want and then press the Y button. This will bring up the leaderboard. From there, you just have to find yourself. The simplest way is to hit X once and the leaderboard will change from the top scores to those near you. You will be highlighted so press the A button. You will get a small menu that pops up and you choose the first option of setting this player as your rival. Then the game will go back to rivals with the track you want highlighted. Press A once and your will be selected, then select your car and race.