The fill line may have crushed around a (too tight) bend or bulkhead penetration, can you feel along the line or otherwise see it?
The 1.5 inch fill line shoud offer no restriction to the flow of fuel from any pumping station, including high speed ones.
Except for some 20 footers since the fill point was low relative to top of tank, heard no other issues unless fuel or water is getting into vent line, then same will occur. or you rocking while fueling.
Is any fuel vapor or fuel dripping down the vent outside the boat?
Keep a 100% cotton rag around the nozzle base