I wouldn't worry about carrying a spare pump, myself. We usually have a big jug of water to service all our cooking outside anyway. I would miss the instant hot water though. One could always drain water out of the holding tank to use in an emergency too.
2017 Escape 5.0 TA (someday soon, I hope
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln