I thought I would share a neat trick I found (also a potential bug if it isn't intended).
If you place a crate directly beneath you whilst in mid-air and immediately jump, then you can jump off the crate, using it as a boost. It is a very quick and easy method of scaling tall cliffs in outside areas when you can't place down platforms.
I've even taken to using the trick for getting around in internal chunks. Partly because its not any slower than using platforms (i have place crate set as the 'C' key) and mostly because its such a ridiculous mode of vertical transportation!
You should all give it a go!