A few years ago I flew REP-(PKZ)-VTE. In PKZ we all walked into the terminal and proceeded through immigration. Those continuing on to VTE were given re-boarding cards and told, when boarding begins, to be in the boarding lounge.

Upon arrival in VTE we picked up our bags and I don't remember ever going through customs because this was now considered a domestic flight.

If you encounter this scenario then there should be no problem making the flight.... As well, if both legs are on the same plane then that serves as your insurance so to speak. Just try to get to the visa desk quickly as typically the first few people to submit their docs/money are through in a matter of a few minutes while those down the line have a much longer wait.