The trick is to add a clause saying something like “if any part of this contract were found to be unenforceable, that part of the contract will be struck out and the rest remain valid”.
That way you can add all sort of weird requirements to a contract, and if in some country, circumstance, or at a future date, some of them turn out to be BS… whatever, you tried, and if anyone didn’t sue you because they thought it was valid, then so much better for you.