If anyone is ever in doubt about whether or not they have enough radiator area to cool their components, just remember: The R9 295x2,
a 500W dual-GPU solution, relied on
a single 120mm radiator and had well-reviewed (if not astonishing) temperatures.
If that
slab of molten lava graphics card can be cooled in such a manner, I'm pretty sure two Nano's and even a CPU will be just fine on 240mm of radiator space. Maybe the temperatures won't be stellar, but they'll be totally fine, and you could probably spin the fans pretty low if you sourced good ones, to boot.