I got a response from Combustion support today:
"We've seen this issue on a few grill models where the stock probe length isn't ideal. The good news is we're actively producing longer and shorter probe options to fit different configurations. We expect to have those options available to share soon. [...] In the meantime, your workaround of removing the metal backing plate and insulation should work. The probe should still read correctly with limited penetration since the sensor is at the tip. Just be careful with the stability since you can't clamp it inside."
Chris also posted some pics over on Reddit showing the 3D-printed stainless steel prototypes. I'm very happy they're working on a longer probe!