The border in AZ is very large, rough, easily hid in and usually wadeable. If you’ve never seen it, that would be a trip worth your time (take plenty of water!). The Texas one is much the same with several crossings for the small communities to cross back and forth; very small areas of swimming - some in the Big Bend Park in the canyons. It’s hard to spot someone on foot - especially if dressed in the same colorings..
I’m in TX. I am familiar with the border.