Decarbonization to mitigate climate change will require a reduction in fossil fuel consumption. The economic effects of moving away from fossil fuels motivates communities that produce coal, oil and gas to obstruct climate policy. How could climate policy be designed to win support for decarbonization in fossil fuel communities? Answering this question requires public opinion data from these crucial regions, but national surveys often fail to recruit respondents from these areas. To overcome this limitation, we deploy a novel sampling strategy -- fielding surveys at Appalachian county fairs -- to access this hard-to reach population (N=248). Employing a multi-attribute policy experiment, we find that policies reducing transition costs, such as investments in worker healthcare and pensions and income compensation, increase support for transition assistance. In turn, respondents report willingness to back climate policy coupled with assistance for workers and community members. The findings suggest that smart policy design can build climate coalitions for decarbonization, even in the places most impacted by moving away from fossil fuels.