Well the denier stance certainly seems to be a winner in this primary season - as it has been for the GOP for years now. But eventually even dumb Republicans will have to acknowledge reality. I haven't seen any polls on it, but I suspect that's beginning to happen a little already.
It didn't help Huntsman to be sane on climate change in 2012. But that was then. And he was never in contention.
Being the first or only sane one this time around could be a smart move while leadership in the GOP race is still being measured in low polling numbers. I imagine if any one of the top 4 or 5 candidates takes a strong, science-based stand on this, it could give him a boost. And Trump's skill at scathingly mocking those who disagree could be just the approach necessary to shake things up on climate change.
You're right that he can't embrace too many liberal positions and still fit among the sock puppets. But being right is only a liberal position because Rs have become science deniers and think truth, facts and science are liberal. If a GOP leader embraces climate science and basically says "don't be an idiot, science is not a liberal plot," he could pull it off.
Imagine Trump saying something outrageous like "I am the most successful man in the history of the universe and I got that way by relying on the best science to help me make decisions. The best science proves that climate change is real, predominantly man-caused, and very, very dangerous. I won't let these ostriches put America's head in the sand and pretend that facts don't matter."