You mention longer pull rods, so you're familiar with that. What is it you're asking? How they work? If they work?
Check the koubalink website for some more info.
Ask a more specific question?
5'7" isn't much on the short side. If you're new to dirtbikes, some time spent getting used to the bike will help a lot. Being able to easily touch the ground will come to be less of a need.
NOT being able to touch the ground will likely be an advantage, anyway. Developing that habit isn't a good thing. A good way to get hurt for one. Getting to trust the bike (when you get the suspension to work as it should) and knowing it can save your arse more often than not if you just LET it is a good thing.