We want to look at 240.21 for this question.
As I read it, you can use the "10 ft" tap rules only within the same panel or gear. Your light would not qualify.
The 25 ft. rule lets you go outside the enclosure....but your wires have to have at least a third of the ampacity of the feeders. Since you're using #3, I assume the supply is 100 amps. This is one of those rare times you can use the full 35 amps #10 is rated for- so run #10 to your 20 amp fuses at the fixture.
