Drew,
Here's the leg on my trailer. Not sure if it can be purchased in the states but it can extend well over 20". The leg is stored horizontally as you see (sorry about the back ground wood pile). To swing down, pull it out and swing downward until it locks. Then squeeze a spring loaded latch to drop the leg down to the ground. To extend it further, release the lynch pin and extend the lowest part as needed and then reinstall the lynch pin.
Stowed position:
Setup position:
Extended position:
Hope this helps.