@sarahfrompittsburgh
I've never had any success getting my black eyed susan vines large enough to cover trellis. The ones I had never even made any seed, always a frost before they had time too. I don't think you will have a problem in that area.
I'm a morning glory fan and grow lots of them. If you find they are coming up too much if you run a lawn mower or weed wacker over them before they get going they wont grow back. I always try and get mine down in the fall before too many seeds set. I know a lot of people hate them for that reason.
You can try ipomoea tricolor, as in Heavenly Blue, Blue Star or Flying saucers, they're not near as weedy as the purpureas. Also Ipomoea nil is not invasive especially here in PA.
