I just had my 24x30x12 metal building insulated with 3-4" of open cell on the walls and 5-6" of open cell on the roof. This building is going to be a woodshop. I live in deep south texas, basically at the border. There's also a 10x10 roll up door which is not insulated but I will put refeictive lining to help keep heat out even though its in the shade 90% of the day and faces north. I need help figuring out what size minisplit to buy. The peak of the roof is about 15ft. Also where should I position the head of the unit? I'll include some pics. Thanks!