I would prefer the border patrol (and the Police) to have different training, different standards, and different qualifications than the average soldier in a foreign land. They are not interchangeable, unless there is war on the border.
Bring the troops home. Make their active service time shorter. Train them and give them experience in trades or other marketable skills while serving. Many jobs outsourced and contracted by the DOD could be done by active duty soldiers instead. If some of them qualify for border patrol after they are discharged, good for them, but it should by no means be automatic. Best for them to have training and some experience to join the job market.