Rebuild the searchlight. It needs a little more space to accommodate a standard LED.
I put the LEDs in brass tubes. This mostly stops light scattering through the plastic. I suggest that getting a pipe cutter (maybe from a plumbing supplier) is best for cutting brass pipe. The bevelled ends on the headlights are a bit trickier. I drilled out a scrap of wood so that the pipe fit in the hole. Then used a hacksaw. The wood stops the pipe collapsing as you saw it. There is still a fair amount of clean up required with needle files afterwards.
I used the whole interior of the Rhino as a battery and switch compartment. The back door and top hatch are magnetised for access.
The paint on this model came out insufficiently metallic for Iron Knights.
The searchlight gives a high angle, which casts decent shadows.