Mike - I will be happy to escort you to whatever picture taking opportunities you want here in McAllen. Payment would be to let me use your Mk III.
Okay - seriously now - I'm not sure I know what you like to shoot, but you sure don't have to drive all the way to Brownsville for nature shots. As others have suggested, Santa Ana is close by, but there is also a butterfly garden in Mission, as well as the old La Lomita chapel to shoot. There is also Bentsen State Park on the river.
Maybe you like street shooting - a quick trip across the border to Nuevo Progresso or Reynosa will get you some good shots. A drive up the river will take you to the Los Ebanos International Ferry Crossing. Yep - a ferry, not a bridge, into Mexico.
Let me know if I can help - just let me know what you like to shoot.