Swift Boats! have you seen the Rio Grande? You would be better off partoling the Rio Grande with ATV's, at certain times of the year it is only inches deep at best. The farmers in New Mexico have been diverting most of the water for years. It is not much of a river. That is one reason it is so easy to cross.
The last time I was down along the Rio Grande in Texas was back in the 1970's. So no, I haven't seen it lately.
ATV's sounds good to me, as long as they're backed up by Bradley's and M-1's.