A radiator surface will indeed work better if its area increases, even in a vacuum. However, it is not a smart thing to put two radiator surfaces facing each other in a vacuum; since there is no convection by a medium to take the heat away from between the surfaces, the radiators will merely be casting their heat to the opposing radiator... Hence, a stack like the ones atop the BoP is not optimal - but it may still be better than a simple flat surface for two reasons. One, it does increase the effective area a bit (although not as much as a "washboard" surface with ridges sloping at 45 degree angles), and two, it may be a good idea to hide the radiator surfaces from the enemy, even at the price of efficiency.
I'd assume our heroes would have to prepare for a long journey home, with provisions for the whales for at least a day of sustenance. Also, I'd think they would have insufficient data on what works on humpback whales and what doesn't - the Klingon computer wouldn't have all that much data, and the species would be alien to our heroes, and doubly so for the resident living computer memory bank Spock.
Timo Saloniemi