I don't use hazards when filtering, seen a few use them. Bigger issue is getting people to actually look in their mirrors, le alone see your lights...
Come across all kinds of tricks here in London: day light running lights, BMW fog lamps, mock police 'Polite' getup, head to toe hi-viz, insanely loud cans, riding around whilst bouncing off rev limiter and so on.
Recently I found out a lot of new vehicles have the indicator permanently on as a solid orange light, then the start flashing when you do indicate. Apparently, this is a common thing that's come from US and it's supposed to be easier fro someone to judge distance and speed bike based on how the solid orange indicators move closer together as you approach. Not sure about this one myself, as in a quick glance it can appear they're indicating and about to change lanes/turn etc.
Personally, I opt for the low gear/high revs stance. In a low gear, you make a racket so people hopefully hear you before they see you, plus you've got more engine braking, from the moment you're off the throttle and grabbing brakes. Then supplement this with the odd pip of the horn if I suspect someone is about to move over and hasn't seen me. Which reminds me, I still need to install that Stebel Nautilus 140dB horn to the bike....