Ship in two boxes?

Suppose I have a store that sells books and ice cream.

If a customer order consists of several books, then I would package it in one package, ZenCart calculates shipping based on weight, I take to UPS counter and ship. And everything is fine.

Same thing if order consists of only ice creams. Fine.

The problem is when an order consists of both books and ice cream. In this case I have to ship in two different packages because ice creams needs to be shipping in a special insulating container (and books can not fit inside it). I don't mind taking the extra effort of packaging the orders into two different types of container. The problem is that when I take it to the UPS counter with two packages, they tend to charge me much more than what ZenCart had calculated. Since ZenCart had calculated based on that assumption that the total weight was in one single package.

What are the suggested solutions to have ZenCart calculate shipping for two separate packages whenever order consists of items from two different categories?

i think what you wanna do is add a flat fixed cost to the ice cream because it seems it's more expensive to ship. i don't think zencart can calculate shipping of 2 packages for a single order. that's what i would do.

I had a similar situation, some items the store sells get shipped separate i.e. posters in tube mailers, other media in media mailers. I just set up each product with attribute 'added shipping', made it a one time fee, and set shipping on the product itself as 'always free'. That way, if someone orders only posters, no other shipping method gets added. And if you order 2 or more posters, the shipping is still the same flat rate from the attribute.

Not sure if that applies to you 100%, but it may gives you ideas.