WooCommerce--Adding Gift - change flat-rate shipping class

Hi,
On WooCommerce single product pages I use flat rate shipping on products that people can customise online.

I use gravity forms so customers can fill in what changes they want - add a name etc… On the bottom of that gravity form I’ve added a checkbox if the customer wants to add a Gift Box.

But adding a gift Box changes the size and shipping Rate for the product.

Is there a way that I can in the background add extra for the shipping - or change the shipping class when someone adds a Gift box?

I could probably work it out with variations or using weights - but I have 100 or more products and I hate to change the shipping calculations if I dont have to.

Thanks in Advance.

Hello. If you are using this plugin to integrate Gravity Forms with WooCommerce:

please contact them for support. Gravity Forms does not handle any sort of integration with WooCommerce, so a plugin such as this one is required. They should know the best way to handle this. If you have any other questions, please let us know.

Thanks Chris.

Eoin