I've heard from several people who grow the vine that once established it can take light frosts. Let's say I planted the vine in the woods in zone 9b - 10a and it became established, could it escape that area and spread? Keep in mind that the woods I'm talking about are disturbed, it's not a nature preserve, although it is safe from being chopped down. This is second growth cypress-tupelo swamp which is no longer swamp, so it now contains the original cypress, tupelo and black willow, as well as bottom land hardwood trees like maple, sweet gum, yaupon, etc. These forests were clear-cut in the 1800s and allowed to grow back, they're now inside of a levee system and dry. The trees are very tall, upwards of 150 feet, with a few virgen trees that the loggers left for whatever reason, perfect for the vine.

Will the occasional hard freeze keep them in check by stunting them every now and then?

There's already so many invasive plants around here, all of which seem to have only one use, their looks, seems like the vine couldn't hurt as much as chinese tallow, chinese privet, golden rain tree, japonese honeysuckle and many, many others already have, choking out all the natives.

Are there ethical implications I'm not considering?

Just to show how bad the invasive are, this is the edge of the woods, notice the mulberry tree to the right struggling for it's existence. It's being smothered by japonese honeysuckle. And the black willow right next to it that's totally over run. A tornado plowed through the spot in the picture during a large hurricane, which was the opening needed for the invasive species. The japonese honeysuckle is so bad that it strangles the invasive trees as well.

Perhaps this awsome oak could support the vine.

Caapi will take over whatever support it can and given the right circumstances could well become invasive. There are stories in Hawaii where the vine got too rambunctious and the stems were all cut to try and stop it but the aerial parts had rooted in the crotches of the trees and the plant continued to spread amoeba-like through the canopy.

That said, frosts will knock it back and given your USDA zone I don't think you'd have to worry about it getting out of control. I'm in 9a and we usually get one or two hard freezes each winter which is definitely enough to keep it in check. Left unprotected it will freeze to the ground but reliably puts up new shoots come spring.

That oak would be good if you want it to really run wild, but it would be difficult to harvest from. I let mine take over a fifteen foot dogwood tree and it seems happy enough, plus I can reach all of it when I want/need to harvest.

a vine with a bad humor can invade even an eucaliptus area. no one stops them when they get really big and large, they grow where any other plant wouldnt grow.

That's good to hear that you're in 9a and your vine reliably comes back each year. I'll grow it at home and get to know it first before I plant one in the wild.

Do you grow mimosa as well? Do you protect them?