You will not be able to do that by using the standard character class.
You can change it if you know C++ or, (and that’s what I’d do ^^), you don’t use the capsule component for collision when crawling but instead, you use another one (or any other volume…) that you add in your BP 
Doing so, the forward vector used of the capsule (used by the movement component and certainly other things) will not be affected and you’ll have any collision you wish.