How do I set up OSC to have multiple shipping boxes for one item?

[jeepcamping.com]

I have the need to set up my store to have the correct shipping for heavy items that are shipped in multiple boxes. The vendor has given me shipping costs per zone but I need them to perform accurately in OSC.

 

Example:

 

I have a lift kit that is shipped in 5 or 6 seperate boxes from the vendor. They tell me that shipping to FL. from the west coast would be $285.00. When I enter the item in OSC the weight is 325 lbs. So the UPS calc on it is $447.00. Totally inaccurate and totally out of the question for my customers.

 

What can I do to resolve this issue?

 

Allen