I personally use arch trellises for vines, or train them onto walls. That trellis should be good enough to support any Ipomoea, but make sure that the vine can grow onto something else, because Ipomoeas will grow, and they will grow quite quickly.

As for moths, I like to watch the large moths that come to pollinate my Daturas. The genus Datura will only be useful to sphinx moths (such as Manduca sextus), but it's quite worth it. I maintain that these are some of the best ornamental plants around.