Would love to beta test a new iPhone.. is there a way to do that

If testing as long as you wish is a problem, and you would like this beta test to be a more short term test, then go ahead and provide your credit card to Apple, and you can test it for 14 days. Make sure you return it before the 14 days are up, or you will be testing it forever, or until you decide to sell it on your own. </sarcasm>

Sure, purchase a new iPhone, then test as long as you wish.