Hello James,
I'm not sure it will work but did you check limit values in WOCR? (Cross-Process Settings >> Warehouse Order >> Define Limit Values for the Size of a Warehouse Order)
If you determine different consolidation group based on routes, you can limit consolidation group to 1 in each HU. (Goods Issue Process >> Define Consolidation Group. )
You may need adjustments on storage type and WPT depending on your customizing. Make sure check these, too.
Best regards
Serhan