Even so there is research on how car design impact road safety, and if there’s a sliver of doubt that that’s sufficient to justify banning the Cybertruck from public roads the tests to prove its safety should be done in a way where gathering statistics doesn’t mean killing people.
Honestly, I believe that in the noisy world this is exactly how you do things. You try it out. We've done it for hundreds of years. If you have good reason to expect drastically effects you are careful of course. I don't think there is a good reason to expect drastic effects from the Cybertruck. If you were wrong you will quickly see problems arise and can cancel your trial. If nothing bad happens, seems alright. This is basically how we've dealt with the safety aspect of engineering and medicine since forever. You can never perfectly predict what's gonna happen.