I added a loop inside the trunk first, thinking that might help, but it didn't make much difference.
The reason for putting the loop in the fender well is that you can get the highest part way above the level of fuel in the tank.
When you turn hard to the left, the fuel sloshes to the right, reaches the level of the vent in the filler neck, and flows into the hose. The higher it has to climb inside the hose, the less likely it is to spill out the end of the hose.
Find a hose that's a snug fit on the little bib in the filler tube and add a hose clamp if there isn't one there already. The fitting on my tank needed 3/16" (or 5mm) hose. The hose that came on the car was the wrong diameter, was much too loose, and there was no hose clamp, either!
Lead the bottom (open) end of the loop as low as you can get it, so that if fuel ever does drain out there, it will drip onto the ground and not down the inside of the fender well.