Acer sieboldianum 'Kumoi nishiki' is often considered a variegated maple that has reliably consistent white variegation compared to Ukigumo which may change dramatically from year to year in its variegation. Although 'Kumoi nishiki' still needs some of that afternoon protection from the sun to prevent burning off the leaves.
This excellent tree with its white and green variegated leaves is considered much more cold hardy than many Japanese maples and you can likely grow it in Canadian zones 5, and possibly 4b. Remember, our hardiness zones do not align with the US zones. A US zone 5 is like a 5b/6a in Canada.
This tree may be 8'x5' in ten years or so.