Our own Ben Pearson's new article in Ars Technica Starman is out there, but we probably won’t see him again until 2047 points out:
A much closer pass will happen at Mars on April 22, 2035. The distance this time will only be about 1.4 million miles (2.3 million km), and has a small chance of being much closer. The predicted error is higher the further in time one goes, but at this point things are still accurate enough to be very confident it will be that close to Mars within three hours of the prediction.
It is theoretically possible that a telescope could be placed on Mars by 2035 that will be able to observe Starman. A one-meter telescope, such as the South African telescope that last observed Starman, could easily do it. With so many new super-heavy rockets being planned, one of them could possibly carry such a payload to Mars by then.
But what if Starman/Roadster had a modest camera, something like a wide field imager used on other deep space spacecraft that perform flybys of planets and moons, as well as some way to automate pointing, timing, shooting, and storing images using a small dedicated solar panel and battery?
Could a hypothetical "Starman Cam" see and image and resolve the disk of Mars in 2035? Or Earth in 2047? Then beam it back to Earth in 2047 or when it next passed through our neighborhood?