Don't skip it just for a lack of head restraint.
I made one up in 2 days that is really sturdy that clamps onto the existing rollcage. Used about $100 worth of materials. The most expensive part was the SFI rollbar pad. McMaster Carr has 1 5/8" ID tube that will fit tight on the rollbar. Use it to make "pinch clamps". Then take 1 5/8" rollcage tube and make a couple "L" shaped bars and clamp them to the cage with the pinch bolts and pad it. Support the L bars in two places so they can't rotate. So (4) pinch clamps must be made, and 2 "L" bars. You can fishmouth the ends with a bench grinder, and weld them on with a cheap MIG welder. Bending can be done at your local muffler shop, or build the L's out of pieces. If you aren't good at welding (like me), you can tack weld it in place, then unbolt and carry them over to the muffler shop.
This way, I can remove them later if rules change, or I need more room to work inside.
