I reviewed and purchased a smaller drone, from WHISPR. Through that, I looked at similar VTOL drones, which OP is demonstrating. In theory, they're cheap:

https://www.uavmodel.com/products/makeflyeasy-hero-2180mm-ua...

This one has a maximum climb rate of 3 degrees. Which means you'd need to plan a route that's continously climbing, and tacking back and forth to avoid going steeply. So you would probably combine flight planning using Mission Planning: https://ardupilot.org/planner/ and custom json tweaking following MavLink protocol: https://ardupilot.org/dev/docs/mavlink-routing-in-ardupilot....

The open source flight controllers and systems are https://ardupilot.org/copter/docs/common-autopilots.html#ope... a good place to start. There's a few orgs building the full experience, but you'll of course pay for fully integrated, but still open source, hardware+software.

The scenario you describe is exactly what a VTOL or normal play is for; quad copters simply do not cover enough ground.

Also consider the camera. DJI typically ship with really low quality cameras, but https://www.bhphotovideo.com/c/product/1785754-REG/sony_ilx_... would get you a much higher pixel density so if you're more interested in the imaging, you can flight higher, near the licensed ceiling, completing more ground faster.

I've also found AI models know how to calculate pixel densities, so it's pretty easy to mock out a flight plan even if you dont have the actual drone available.