There is also the SIM tray and the mute switch, not to mention the lightning port and the speakers. I tape over the mute switch and SIM tray and if I had wireless charging I would ytape over the lightning port too. AppleCAre+ is a good idea too - anything to reduce the risk of replacing the phone entirely as water damage is not repairable.
Cases themselves carry the risk of holding water close to the seals, so taking it out of a case until both are dry is advised after a water incident.
But best advice is not to get it wet or subject it to trauma, and carrying a phone while sledding poses both risks.