I am way outside of my comfort zone here and my comments are targeted strictly on the engineering side!
Standing, represents the most demanding issues regarding loading (over all strength) as loading points become smaller and heavier (the difference between laying and standing). Add movement and the structural demands skyrocket. Kingsize beds are commonly lower to allow an adult to swing their legs out as they step on the floor to get out, rarely are their frames designed to support jumping,
Toddlers tend to jump out of bed just because it more fun, as a result, Age transition beds tend to target lower heights or adjustable heights for the high-end multi-year designs that grow with the child.
As noted by the Warning supplied by
BobbiSueEllen, his construction does not meet the latest Government specifications. Great care must the taken to either grossly increase the structure or limit activities like standing, jumping, etc. with higher height settings. As the height become lower like an Adult level King-size bed and with an heavy duty frame, the increase strength allows for more activities.
Enjoy!