Laying the seat back as much as possible and lowering the seat can help. Just don't get so low the torque tube can hit the seat. I'm not a big fan of the add on halos that is becoming a popular thing for guys to do. There is no support under them and causes the cage to become compromised when it strikes the ground.
Nick Landon
The ones I've seen are more wedge shaped kinda like and increased angle of the downtubes many guys then make the visor on the right side go up to it so you can't even tell it's an add on
Halo's are not legal for use in Australian Midget racing. Head clearance isn't just about your head not hitting the ground in crash but also having bar work as far away from your head so that when it does bend in a crash you still have room.