My friend made his own heated vest for riding his motorcycle in the winter. He stitched phone wire into and old shirt attached it to a quick connector and added a fused connector on his bike. He regularly rides in the 20-30s if it's sunny out. There are plenty of how to's online to help figure out amp draw using ohm's law based on your wire resistance and length. You can shape the wire to anything....even a steering wheel.
Bill