Measure the product, not the pallet
The commonest reason customers move off a standard footprint is overhang. A load extending even an inch past the deck transfers weight into the packaging rather than into the pallet structure, and corrugated compression strength drops sharply. The damage then appears three handling events later in somebody else's warehouse.
So the first number in a custom specification is always the loaded footprint of your product, not the pallet you currently use. We will work backwards from there, including the possibility that a standard size with a different case pattern solves it for free.
