For me, open borders with easy documentation.

We survived for decades with basically just that. People could come up from mexico to work the fields in the summer and head back for the winter with basically no friction at the border.

The question to ask is "what is the border actually protecting"? When you start to drill in the reasons for a strong border, they all end up being fabricated problems.

"To stop drugs". Well, most drugs are either being manufactured in america or they are brought in by US citizens not smuggled across the border.

"To stop human trafficking". The ironic part here is the most common human trafficking happens because of the strong border. "We'll deport you" is used to keep workers abused. A weaker border gives workers much more bargaining power.

"To stop crime". Most crime is done by citizens of the US, not immigrants. And, again ironically, overly punitive borders does exactly the opposite of stopping crime. When someone that's undocumented can't talk to the police they are far less likely to be a witness for a crime or to report a crime. It further encourages gangs. A lot of gangs spring up because people can't go to the cops. That's part of the reason the mafia flourished. It's the reason militant organizations like the Black Panthers were formed.

"To create jobs". This one might be a wash. However, it has to be said that more people means a higher need for services in areas which can in fact create jobs.

"To avoid spending on services". This just doesn't happen outside of maybe emergency room care. Undocumented workers are FAR less likely to use any public services because they don't want to be deported. And so what if they do? Is it really such a bad thing if a non-citizen gets an education here? Don't we want more skilled and educated residence?

Let me put it in contexts of other countries. I as a kid, made a few trips to Canada and back. Back in the day you could do that without even presenting passports, it was kinda wild. Did Canada suddenly explode because of that easy border crossing? No, it was just a non-issue.

Similar things happen in the EU. The relaxed border controls for EU members hasn't resulted in chaos. It is, for the most part, a non-issue. People generally do not move, you still have most people born in whatever EU nation they are from staying there. The same would be true of the US.