Be aware of your flash frequency. Some are very slow, eg 2 Hz (flashes per second) , resulting in about 1/2 second of unilluminated travel.
This is really dangerous when approaching a side road. The driver will glance at you, not see you, look the other way and pull out.
Higher frequency flashes can be seen OK but I always use the front on solid. If you want to add an additional flashing mode light, that is fine.