I was wondering if there is an extension available or a fairly easy way to make it so the weights of items with free shipping are not added to the total cart weight when live rates are retrieved from our carriers but only when there are other items in the cart that are not eligible for free shipping.
Here's what I'm working with and what I've tried.
Magento CE 1.9
I have a shopping cart price rule setup to offer a free shipping option only when all items in the cart are eligible for free shipping.
I have tried editing Validator.php in /app/code/core/Mage/SalesRule/Model to adjust the item weight to 0 for each item that is eligible for free shipping. This works as expected when the cart has both calculated shipping items and those that are eligible for free shipping. The issue with this particular fix is the free shipping option and no paid options are available when the cart contains only items that are eligible for free shipping. Please advise.