The main thing to understand is that you can not use TurboTax to prepare your PR return. (which would be the equivalent of a state return if you were in CONUS). As for filing PR taxes, I fully expect you have to. Since you do "in fact" have income in PR, the only way possible for PR to know it's not taxable, is if you file a PR return. Otherwise, I'd expect PR to fully tax every single penny of income produced in PR.
Be aware also, that you will need to prepare and file your PR return before you can even start your federal return. That's because any taxes you pay to PR are deductible from your taxable income on the federal return.
