Caveat: I should have remembered but didn't because I always think the side marker lights are run and brake; but, they're run only.
Soooo, if you are splicing the harness under the seat, splice the brown and violet ahead of any module. You'll have just a turn signal function; no run or brake light function. The saddlebag spoiler LED's were intended for run/brake function (so somehow the LED's were set-up for two intensity levels) and adding the turn signal function didn't involve any intensity level change for the LED's from what they were intended for; the side marker LED's aren't set-up for dual intensity--so I don't know how wiring them for run/brake/turn signal function will work.
Carl