Trim-lok makes a drip rail that looks legit. This attaches with an adhesive strip that it claims is super heavy duty. A lot of people use this on RV's as a faux gutter system, and seems reasonable for above windows when cut to size.
Clean the siding really well where it will be attached, peel, stick, done. 25 feet on Amazon for 60 bucks with shipping, might be able to find locally for less.