I've stripped a M5 thread in a 3mm thick motorcycle swingarm. The thread inserts I have are about 5mm long and when inserted into some 3mm scrap they overhang the other side by about 2.8mm. Since the swingarm is made out of a box section, I can't trim the overhang off from the other side.
I've tried cutting the helicoil down to size, however the thread wasn't smooth and tended to bind up when inserting the bolt.
I've been able to apply a reasonable torque to the bolt without issue so do you think it's ok to leave the helicoil sticking out the other side?