Looks like a lot of faffing about , is he willing to pay your sewing time as well? Iv actually got some polishing clothes that are very thin from an Irish guy called Tadgh , a lot thinner than microfibres. Even if you sew ribbon on either side and polish it (like your polishing shoes) , you’d need to be on either side of the glass at the same time . Unless there’s 2 of you , but then it comes down to cost and whether the customers going to pay for it