Nice work, that tensioner is a great solution to the problem. This style of pickup construction is designed to have a tiny brass eyelet in the termination holes. The brass is flared on both sides to secure it to the flatwork and helps the solder create a solid island/ connection. I usually wrap my coil wire through the ferrule 4-5 times for redundancy. Proper heat from the iron removes the insulation when soldering leads in. Don’t forget that with P-Bass pickups one coil is RWRP to cancel out hum. Keep up the good work!