What I did and improved in the last two weeks:

• Designed, ordered and used a professionally printed board
• Changed the motors for bigger ones (a bit more slowly rotating)
• Thus changed the prototype chassis to a much wider one - it is now too wide for practical use I think
• Debugged and (partly) found an odd Wifi transmission problem: The camera interferes severly with Wifi transfer
• Written an Android app for image display and remote control

Now there are some problems still or newly open:

• The camera interference is not solved (https://github.com/ArduCAM/Arduino/issues/301) - I improved the situation a bit by using an aluminum shield between camera and ESP32
• The motors are very different (left and right) and generally without any control over them (-> encoder) the movement cannot be sufficiently controlled
• Delay from the camera capture (200ms at least) and the poor Wifi transmission make a very sluggish image transfer and thus the control once the vehicle is out of sight is nearly impossible

But still: Something moves remote controlled!