The question that this thread generates is: What does a Japanese win on Guadalcanal gain them? Guadalcanal would still be vulnerable to air strikes from Espirto Santo by B17 and B24 aircraft and could even be escorted by P38's. So, their position is still vulnerable, they would have to invest a good deal of resources to maintain the island, and would not be gaining any strategic value from having Guadalcanal.
On the whole, even if the Japanese win they lose.