Hi Scott,
excuse me for not being able to help on your code-related question.
Regarding the suggested application, you might reconsider to use a common airspeed-sensor with T-tube connectors (splitting total and static pressure between the airspeed sensor and your MHP-sensors). An advance of such a straightforward approach would be the observability of your sensors and their (spectral) errors. In addition, you might benefit from all the efforts and insights of the community which uses “normal” airspeed sensors (TAS<->EAS, ARSPD_RATIO<->PCORRECT, in progress: AP_Airspeed: switch to PCORRECT factors instead of ratios by tridge · Pull Request #17987 · ArduPilot/ardupilot · GitHub)
BR, Konrad