Explanation
Creating a criteria-based sharing rule giving the Retail Sales role access to Accounts of type PersonAccount is the best option to meet these requirements, as it will grant access to all retail customers based on a field value, regardless of ownership2. Creating an owner-based sharing rule on AccountContactRelation will not work, as it will only grant access to account contact roles records owned by retail sales reps, not all retail customers.
Updating the Retail Sales profile to grant access to Person Account record type will not work, as it will only control the record type visibility, not the record visibility.