SM-6 is a cinch, no-brainer, true plug and play on K-style switch bikes with a 15 pin plug.
But I'm puzzled by your brake light getting activated. Sure you didn't tap into the brake circuit by accident with the resistors?
Current: 93 R100GS, 04 XR650L
Prior: 73 CB350, 77 R100/7, 83 R100RT
I love every motorcycle I've owned and even some that I haven't.