The gauge really can't be relied upon, at the end of the day if it's not overheating 99% chance it's perfectly ok, if it is a very hot day and going slow enough fans will take much longer to go off and be on much sooner purely due to less cooling effect as the ambient is that much hotter.
I know on a really hot day when driving mine with the old rad and air deflector on it could take well over 5 miles at 50 mph to cut fans off once started after having been sat in traffic, so I binned the deflector, massive improvement.
Some things you can do to help is to panel in the rad between rad and bumper anywhere air can escape instead of going through the rad as air will take the lazy(easiest) route, but certainly shouldn't be needed on a std set up in good order.
The 4wd set up is vastly better purely in flow terms from the pump, but a well maintained 2wd system is perfectly adequate.
tabetha