I realize that it's lower in the cooler ciruit, and how much pressure is neoprene fuel line rated for when it's hot out with hot fluid running through it.
Chris,
I said hydraulic hose as a coverall but I'm pretty sure there is something in between fuel line and commercial hydraulic lines that would work fine.
Like this,
http://www.summitracing.com/search/product-line/advance-adapters-flexible-transmission-cooler-lines