stingers - how small a gauge?

I know it's better to err on the side of caution, but I suspect that I've been carrying around extension cables that are far heavier gauge than I really need. (Result: excess baggage charges, and carrying fewer runs of cable because they are so bulky and heavy.)

I'm wondering how small a gauge I can get away with, safely, for 25' runs of stingers for a variety of loads: 200 watts, 500 watts, 700 watts, 1500 watts. I would guess the answer is 200 watts: 16 ga., 500-700 watts: 14, and 1k and up, 12. I've looked up the answer online, but I'd appreciate a "real world" answer as well.

Thanks!

Bob C