I think you need a bigger stove for that area, especially uninsulated.
Go straight up through the roof. It is easier, faster and much cheaper and a better chimney.
Check your craigslist for double wall pipe. Often a wood burner is selling and the pipes are in good shape from wood. Single wall up to ceiling, then support piece followed by double wall to roof and through. The hole in the roof is no harder than hole in the wall, maybe easier since there is no siding to cut and provide drip edges, not as scary as you think. Locate the hole positions with a plumb bob to miss beams and rafters then cut through roof shingles and all a square hole. Slip flashing piece under a course of shingles, nail down and assemble pipe. the flashing provides side bracing up to three feet above roof.