Very few vines will extend to that degree and still be able to be grown in a reasonably sized container :-) Lots of top growth (and 20 feet is a lot!) equals a lot of root growth to support it. And container grown vines are not exactly "low maintenance" :-)

If you had something the size of a half whiskey barrel, you could try a honeysuckle (I'd suggest a cultivar of Lonicera periclymenum, like 'Scentsation' or 'Peaches and Cream' or 'Serotina') or Clematis montana (early bloomer - spring) or a wisteria. In a container situation, wisteria is not really "intrusive" and most are sold as grafted forms so ready to bloom right away. But of any of the vines, wisteria is the least 'low maintenance' (frequent pruning required) and needs a good sturdy support system.

Beware of honeysuckle (at least whatever variety I have, white/yellow flowers). It will take over your world. I am currently hacking, pulling, cutting a monster that has grown on a chainlink fence, moving up two trees and is invading some flowerbeds. I have been pulling some vines that are growing on the ground and they keep going and going, at least 30-40' long!

Not all Honeysuckles are created equal. Lonicera peryclimenum is not that rampant. Perhaps you have Lonicera japonica, cakbu?

Sounds like you have Japanese honeysuckle, cakbu. Terrible stuff. OP, I have lonicera x heckrotti 'Goldflame', which has beautiful pink trumpets with tinges of orange/yellow flowers. I planted it along a fence last year and it took off. This year I had to dig it up and pot it while I await a new fence installation. I would have waited to just transplant it but it has grown so vigorously already that I didn't want it getting any more tangled in the fence. I can't speak to its long-term longevity in a pot, but in the week or so I've had it in one it has put on a ton of growth and is just starting to flower. I would think that if you gave it a big enough container it would do well. Twenty feet is a lot of space to cover, though.

How about if you just use a couple of plants in a couple of half-whiskey barrels so one plant doesn't have to stretch the entire distance?