To overcome this issue I created 2 Pallets. I called one "Pallet(500kg)" and the other "Pallet(1080kg)".

I still think the best is to have a Packaging section under purchasing that is similar to the Packagin under the Sales.

I'm sorry to post without having an answer, but I have run into the exact same problem.

I also would rather see the UoM conversion assigned on the product level also. We may have 100 different products we purchase as a Box UoM (and we inventory as Each UoM) but, depending on the part, each Box could contain an Each quantity of anywhere from 2 to 5,000.

When I looked into this it looked like you had to create a specific UoM for the product. To set up a product specific UoM on "global" UoM table seems to defeat the purpose. It makes sense that 1 product can only have 1 UoM, but each UoM should be able to have a many to 1 product relationship. However, when the UoM conversion rate is assigned on the UoM level and not the product level, it doesn't seem to be possible. 

I think there are third party apps that might allow product specific UoM conversions, but in my opinion this should be a core feature of Odoo. However, there may be a reason why it was created this way and I'm just now aware of it.