I don't know if this is starting to sound more like Wile E. Coyote (get a crane, suspend a safe from it, and...) or Bill Murray in Caddyshack (try dynamite).

In any case, if you kill it under the porch, you've got stink, which is annoying, but is also bait for other critters. If you kill it outside the porch, you have to get it there, acquire the means to snuff it, then dispose of it.

It just seems like the least labor-intensive solution is to get it out and board up the hole. If you just get rid of the skunk without sealing up its entrance/exit, something else will likely move in.