I grew mine in a big pot. I layered weed cloth underneath the pot on the ground and let it extend out a way from where the container sat but the roots still escaped. However, in my situation, they were never a problem and the new growth was very easy to contain. For the few shoots that came up outside the pot, I simply pinched them off. I believe being in the big pot did help to contain them, just not totally contained. I finally removed the entire pot because the vines just grew too big for my small garden.

I don't know if the vines will hang down from the pot on the ledge but would think they might. Having the pot set on the ledge, I'd think there would be no place for the roots to escape to as they would need soil to spread. The vines don't twine but they do have the little tendrils that will grab onto something, if available, including themselves. Their tendency is to grow upward, of course, so once they grab hold of themselves, they may climb back to the pot! :-)

You can see one of the tendrils they produce in this photo of a maypop fruit.

... Mary