So have I. What "evidence" do you refer to?
Why dont you tell us how much security there is in the park, and outside the park leading into the USA and major highways in Texas?
You tell me. You know better, remember?
You obviously don’t have much knowledge of the area. The river area around Boquillas and Lajitas are filled up with vehicle trails that the parks people don’t acknowledge and will not patrol.
There is one border check point outside of the park leading to major highways within Texas, and that one is easily walked around.
Good enough for you?