Welcome to BLF!
You are asking quite much and thus not receiving many answers.. 400mm hand held requires pretty good illumination and especially the 150m distance is a tough requirement.
Let's assume you would require a modest 100lux (which equals to very dark overcast day) @150m => that would require 2250kcd (more than double the amount of what a very very bright led thrower would give you).
A good thrower would give you 100lux at 50m, but that wouldn't be under 20cm in length or very light either.
You would probably like to have a Neutral White emitter too.
One good alternative for night time photography is BTU Shocker NW, but that's definitely not small or light.