I have backups but the turnaround time never seem to be that big of a problem.
It could take just about as long to get a loaner camera shipped as it does for your camera to make the round-trip.
I have had offers for loaner/lease cameras through local distributors, but never used them.
I have always had a professional relationship with Flir and they have gone above and beyond to turn my camera around as soon as possible (sometimes getting unavailable parts from another camera).
There are a lot of cameras that are in for service that don’t get used but once a year. If you ask nicely and be truthful about your dependence upon your camera, they may have alternative options available.
They arranged to have my camera in Nashville to be picked up on my way through to a week long job in Atlanta.
I did a job at Trane /Ingersoll-Rand when the facility engineer lost his camera (still under warranty). He had a new camera in hand in 24 hours. I guess it’s who you talk to.