Having pulled four tours on the Iron Curtain in the Rotz-Weiden sector of the [then] West German border in the 1960s, I'd prefer we have a 5KM zone, as the Germans did, backed up with both a border patrol [Bundesgrenzschutz AND a military presence as needed.
I was fond of their border patrol vehicles, too. The ones with the 20mm cannon were particularly well suited for the job.
The cab on http://www.panzerbaer.de/helper/pix/bgs_sw_1_mowag-001.jpg seens to be waaaaaay tooooooo high and a natural target. I hope that glass will stop a .50!
>>, I'd prefer we have a 5KM zone,<<
That would lead to a large eminent domain takeover of private property which would only give the FEDS more of a bad name and a lot of unhappy citizens.
Now 'the more of a bad name' might just get a few governors to actually stand up straight again in the name of states rights, not a bad thing at all IMO.