Haha!
Fine, I’ll have a go. No 3rd party anything in mine…
The boat rocking on the water (the hard part!)
Deform the high res water plane with runwave, use XP2 to ‘stick’ the boat to the water while moving it forwards (ive done this before, but not on a deformed surface… I hope it will work). The problem here will be getting the angle of the boat on the waves right, there are a number of ways you could fake it by simply keyframing but that doesn’t seem fun, someone help me on that one
– I don’t know the math to do it in XP…
Rain with PPB, rendered out on a separate pass with motion blur. The splashes could be done with PPB but they might look a little skeletal, maybe if you attach enough emitters to the side of the boat with varied settings (no EI to test!)… Blobby would be too slow, could use a nasty ugly transparency map on a rotating sphere… forget i said that. How about a smoker? Now were talking, use one of them for spray, a really sparse fractal pattern would probably look REALLY cool for that effect…
I would use a luminescent lantern for the cabin light, that way GI would see it as a light source and bounce the light around. I might put a tube light in the cabin, with a dropoff just round the cabin -and make it low intensity- these things create a really cool glow effect.
I would add the boat to a couple of nulls to add some repeating movement noise using the FCE.
The distant clouds would be on a sky dome, or, if i had time, i might use smokers, but they look a bit rough and ready for clouds.
Lightning? Are you kidding!? 
I’d do it in post! Maybe create a number of lightning pictures in Photoshop with alpha and flash them up occasionally, you could randomise it with XP2 (map them to the sky dome on top of the cloud map (in the luminance channel, have XP2 randomise the rotations of the maps so that the lightning doesn’t strike the same place twice!).
So, basically, use XP 
Right, now there’s something for people to take aim at… go on! Improve on it! 
Ian