I can only speak to what a late model caddy had to do they started out with something that looked very similar--- they had to tie the bottom of the legs front and rear legs together, run one between the two rear at the bottom legs run a floor bar from back lower cross bar, to the highest point front cross bar that ran from bottom of legs up over tunnel to the other front leg. Then ran tubes under the drivers seat between the lower preminiter bar and the floor bar---
bottom line in my opinion you will end up with something that looks very similar to the diagram in the rule book---
if the car completely blows up and apart the driver will still be inside the cage with their legs contained by the funny car straps and their arms with the arm straps--- their head contained by the seat side bars and HANS ymmv