The daughter would have no problem. She is young could easily jump that far. Send her out first and then have her help her brother.
bukhrn 's video link shows feet first belly down and use a blanket to keep the sharp window ledge from hurting you. That looks like the best way to me.
But, my TT is so small I am not be worried about it. I can make it out the door. If I couldn't it would not make any difference because the emergency exit window is on the same end of the TT as the door. So it doesn't really help me.
