Handling fee only on certain items

I sell pet food. If I ship frozen foods there needs to be an additional $25 charge for coolers and dry ice per 50 lb order in addition to normal freight. How would I
go about setting this up for certain items only. I have over 500 products and this would apply to only about 100 of them. https://www.wholesomehound.com/index.php

I am doing this manually for now and not shipping anything frozen through the website.

What shipping methods are you using on your current site?

Can this be done via added weight on the product(s)?

I am using UPS XML. I have USPS but only use it for APO/FPO orders. I don't think it can be done by adding weight as the $25 extra fee is a single charge for up to 50 lbs. If they only order 5,10, 15 etc, the same fee applies.

How about by attribute using the one time attributes?

These apply charges once per product vs per quantity ...

I don't think that would work. If they ordered 5, 8 lb packages of the same product it would only add one small upcharge. I need $25 added to all raw food orders up to 50 lbs. If they only order 10 lbs the $25 still applies.

Ajeh, I do appreciate your thoughts and time. Keep the ideas coming.

If I order 1 8lb package what is the extra handling?

If I order 5 8lb package of the same product what is the handling?

If I order 7 8lb package of the same product what is the handling?