With an open canopy at large scale there is no cheating the harness. 1:32 fabric seatbelts for aircraft models, laser-cut from microfabric, carry printed stitching, buckles and the natural creases of a real strap. There are sets for named types from the Albatros through the Mosquito to the Bf 109, plus universal harness such as the British Sutton pattern.
1:32 shows the seat at full size, so this is where fabric beats etch most plainly: the strap drapes over the backrest just as the pilot threw it. Assembly instructions and the universal sets are covered in fabric seatbelts for aircraft. To keep the interior to one standard, add 1:32 instrument panels, and find the machines themselves in 1:32 aircraft model kits.