How can I trust my fellow competitors to record honest measurements?

That is a good question! While we hope everyone plays fair, we can't guarantee that's the case for everyone. One way to remedy this is to create a private contest (only those you invite may join) over a public contest (anyone may join). In a private contest, you'll likely know the people you're competing against and can hold the entire field accountable. In a public contest, you may not know the identity of your competitors, which means leaning on trust in your coworkers is more important.