If we can avoid massive collective issues that would be appreciated as there is very little agency the individual has to address those and that helpless ess can often extend to the more solvable individual matters we all grapple with but also occasionally rise to conquer.
https://www.reddit.com/r/VanLife/comments/1avrsbd/rooftop_solar_tracker/
Looks like someone out there had the same idea.
https://www.roboteos.com/shop
They’re currently selling a packaged system for ~$5k, which is a bit pricey, but maybe worth if you’re full time on the van life. Looks like you could probably fit 2 of these units on a typical roof, obstructions permitting. Alternatively you could do one tracker and one flat unit.
It looks like ground based 2-axis tracking systems can be found for ~$500-1k, you’d just need to bring your own expertise to mount it to the roof and program the controls yourself.
Semi-unrelated: others mentioned painting your van white (which you already have) but I’ll raise you one better - consider painting it with an IR-Emissive cooling paint, e.g., https://i2cool.com/
There’s unfortunately few products on the market at this time, but keep your eyes peeled.