Lighting is important especially if visibility is impaired such as, dusk, dawn, or night time, street traffic, long tunnels, etc. Even with all my flags and ribbons I use a flashing red beacon on the back of my trike especially when I'm on a city street. Flashing lights do get attention and that's good for a low profile vehicle like a trike.
Searching for lights to purchase online sent me into sensory overload! Ratings were all over the place and I preferred to see something in person to make a selection and I found it accidentally.
For $3.99 at a Harbor Freight store, which I haunt frequently, here in Springdale (AR) I found a triangular emergency light (Item 62157).
It's 3.5 in / 8 cm on a side, uses 3 AAA batteries (2 screws to change), has red LEDs around the edges and white LEDs in the center. The power button cycles through three clicks: 1- solid red all around, 2 - solid block of white in the center, and 3 - flashing red all around. It has a sturdy hook on the rear that I attach to my rack with a couple of cable ties. This thing is bright!
The batteries seem to last very well on flash. And, I can tell when the batteries are getting weak because (click 2) the white group comes on a bit slowly and not as bright as usual. I actually have two of these units so I can swap them when fresh batteries are needed.
I even keep a spare in my panniers just in case. I could use it as a separate emergency beacon or a flashlight if necessary. And, because the power button is exposed I taped a plastic bottle cap over it with electrical tape to keep it from being accidentally turned on.
For head lights I use two Harbor Freight bike headlights (Item 98397) for $9 each mounted side by side on a bracket at the front of the trike. This device has three very bright LEDs and runs on three AAA batteries (1 screw to change). It comes with a very good adjustable mount that is both sturdy and flexible.