The original side seam pockets were eensy weensy - even my thinnest winter gloves would barely have fit in them. So I enlarged the pockets by tracing the original pattern piece onto wax paper and sketching in a larger shape. Before cutting any fabric, I held the new pattern piece in place against the coat to be sure it wouldn’t interfere with any other portions of the design.
To keep the pockets from sagging open, I reinforced the inside edge with twill tape. That stuff doesn’t stretch at all and is great for adding stability. I’m pleased with the the way the plaids match up along the side seams. You can barely tell there’s an in-seam pocket at all. Unfortunately, the pockets do gape a bit when I move around. :( So sometimes you see these silly-looking flashes of pink. I might go back before this winter comes and retool the pocket area, perhaps swapping in a darker backing. You learn something new with every project!