The narrative is pretty easy to get. A guy gets sick far from home, dreams of someone he knew and loved, and revives far from home, and far from the object of his dream. But there's more here.
The juxtaposition of sickness and health--viva mexico against sick and broken--is easy enough. But why sick in the dream world as well (right now I'm feeling bad)? The road to ensenada being wide and fast is an old Christian idea. It's the road to the underworld, paved with good intentions (all your good just comes undone). Alvero needing to stay between the lines is a high-road kind of idea, and we get the feeling Alvero doesn't quite belong in the underworld.
There's a Dante-esque idea floating around here. The sisters at the borderland read at first as nuns or beggars, a pure western feint, but they're easily the gorgon sisters as well. The image increases the tension between Dante in the Divine comedy and the narrator here.
"Turn thyself round, and keep thine eyes close shut,
For if the Gorgon appear, and thou shouldst see it,
No more returning upward would there be. "
Gabriella sounds, to my ear, anyway, more Italian than Mexican--it could be either. Tijuana is typically portrayed as a sinful place for bandits and exiles, but it's name is rumored to have come from a woman, "aunt Jane," who helped weary travelers. Again, the idea of the escort and of the alien traveler.
But, in good country form, Lovett does Dante one better, as his narrator promises to return. Moreover, he knows the way out himself, and doesn't need some beatrix to show him the exit. This is somebody who's comfortable in the underworld, more like Hades than Dante. And, like Hades, his pretty sure he won't last long above ground.
At its heart, this is a poem about a person who refuses to act right. The famous inscription leading into hell was, after all, "abandon all hope ye that enter here." And it makes sense that someone succumbing to the temptation beyond the borderland--the sickness, the contempt for life (as you breathe / you ain't no friend to me), the disdain of love--should abandon their hope. But there's no such thing here. The protagonist is leaving now, and has come to grips with his inevitable return.
That move, from sin to righteousness and someday back to sin, is country defined. Imagine Johnny Cash waltzing through the eighth bolgia, both better than and no better than the pimps and panderers.