Product features that aren't attributes

[tozz]

We're selling a product which has a few attributes, as part of our checkout flow we would like to add installation as an option, but I haven't found any good way of doing this.

My idea was to have installation as an attribute, but since Prestashop then requires a load of extra combinations with individual inventory status this is not viable.

 

Does any one have any idea on how to do this? Having installation as a separate product is really bad UX and would confuse customers, it would also be very hard to make it feel integrated.