Recommended Autopilot for retrofit

[AppSciTec]

Greetings,
We are looking to upgrade an existing UAV (Watts Innovation Prism Sky) that currently uses an Auterion autopilot and Doodle labs mesh rider radios. We absolutely detest the Auterion, and want to change the autopilot to an AI based controller for obstacle avoidance. We have the full parameter list for with unit in PX4 and Ardupilot. We use heavy lift UAV's to perform remote water sample collection at mines and other hazardous waste locations. One mine, has a very steep, very deep pit lake that is causing us issues with GPS. The view to the sky is so restricted that we have very low number of satellites and thus our position hold goes wonky (wandering up and down). We use an Aintsein radar range finder to measure range to the water surface, but want to integrate other sensors to keep the UAV in a stable position while operating. What equipment of yours do you recommend? I was thinking a VOXL 2 to use as the auto pilot combined with cameras facing out for positioning in the pit? Would 4 cameras be enough in conjunction with the radar rangefinder looking below? We have tested Lidar sensors and they do not work over water, do you know how an imaging sensor would work over water? Thanks!