That's legit castrau5. However I have a trussed roof not a hand stacked roof. So attics kinda rough I like ur idea. I actually like the idea of a mini split. But have to see what the costs are for building the shed as I am doing probably 12 in walls and sealed room. This my first attempt at growing but I have done enough things to know if u set it up right the first time it's one less thing to worry about. Power here is cheap 11 cent a kW. But I have solar so it's free. I have 17.75 kW system on my home so it's free