EDIT: I didn't watch the whole video linked below until after I posted this. It's for a Reyes head unit, but it is using the same app as DuDu7. At 3:45, it tells you exactly what each setting (except for offset) is. Additional guide https://teyes.ru/pj/
I just got my 11.5" Dudu7 head unit and I've been struggling with getting the 360 cameras calibrated. I found this video which appears to be the closest to having all the same settings as the Dudu7 360 app. I'm at work, so I won't be able to set up the calibration again for a day or two to test out these findings
From what I could gather, these are the corresponding settings
Captain = Car Length
Front Track = Front wheel center to center distance
Back Suspension = Center of rear wheel to rear bumper distance
Rearview Mirror-Head = side camera to front bumper distance
Offset - this is may be the distance from center that the front/rear camera is mounted, but it would not make sense for the side cameras there is no real center. It could also mean how far from actual length/width of the vehicle. On my truck, the front and rear cameras are set back about 15 cm from the end of the bumpers, so I'm going to try -15 offset. The side mirror cameras are 10 cm away from the body, so I'll try +10 offset. If those numbers don't seem to work, then I'll try setting the side offset based on distance from the side center of the truck. In this case, my front camera would have a 0 offset while the rear camera is mounted on the tailgate latch with a 4 cm offset.
As for the cameras. I know the 2053 are more common cameras, while the 307 refers to the Sony 307 cameras which have better night vision. Usually the camera body has the number on it. If it doesn't, assume it's a 2053.
Hope this info helps someone until Mekede can come out with a proper calibration guide