Below is what a hard turn looks like with two full sized bikes mounted on the tongue. Note that the rack is mounted as far aft as possible above the battery
which is behind the propane
This works the same with my Ford Escape
and actually about the same with any normal TV.
I have seen others loose taillights and suffer body damage when they have built a tongue rack too far forward.
Your idea of using your rack exclusively for children's bikes may well work OK (I haven't tried that). They are much shorter.
Perhaps that design might work also if the wheels were removed from short wheelbase road bikes and placed parallel with the bikes between the down tubes and the headsets. Even then there may be some concern for the handle bars on the forward bike.
Please forgive my comments, they are not intended to be critical or to rain on your parade, but merely to be cautionary and perhaps prevent some grief which I have already seen in other tongue racks.