The main problem isnt so much simple turns (like a 90 degree turn), it's doing a full 180, which in some situations can be a necessity for a variety of reasons. Cant really be done in a way that's viable though.... the radius of a U-turn is simply far too wide. I'm not sure what to suggest for this.
How about loops?
Most games with this sort of movement style have some sort of special movement commands you can do. I'm not sure if TLF needs or would benefit from that, but if 180 turns are a specific problem, perhaps adding just the one special movement where you do not change your movement vector THIS turn at all, but end up pointed 180 degrees in the opposite direction for NEXT turn would work?
(Essentially, you go forward at, say, half speed, and in theory you are looping up in 3d space, and then next turn you're counted as moving at that new speed in the exact opposite direction. A diagram would help, but I don't have time to make one at the moment.)
Other possibility:
If you call a full stop (or are stopped due to using an ability), maybe next turn you can move in any direction without a turn radius? That would be even simpler and easier I imagine, and have many of the same tactical considerations...
