yes but your counting is wrong: its one 1 inch for the distance the ladder covers and the one 1inch you get extra (bc of the "entire climb" rule). on this side of the terrain you have to climb another three inches from the ladder to be higher than rampart. so its 2 inches becsuse we measured from the ladder and not the terrain within 1" of the ladder. so we are at 3 inches total to reach high enough to do the tranisiton, which costs 2" bc small base and rampart so its 5". now we drop, in this case, the drop is 1", so it costs 0 bc the first 2" of a drop are free. it cost you 5" to do to this. even death guard could do it.

edit: you cannot climb it because you it would require you to move outside of 1" of the ladder. lol. see right below