Since you do not have a rulebook, the following is from the 2008 book. Comply with the rules and you should be OK for the next two meets:
3.A.3 Driver’s Helmet Support:
A side and rear helmet support system shall be used in all vehicles.
Forward movement: SFI 38.1 systems are encouraged, however, they shall be “engineered” as an integral part of the entire restraint system, inclusive of the seat, safety harness and roll structure.
Lateral movement: The structure shall provide restriction to lateral head movement of less than 2 in. per side.
See Section 3.B.1.
Rear movement: See Section 3.C.
3.C HEAD REST:
A padded headrest shall be installed in all vehicles to prevent whiplash. All drivers shall have the padding within 2 in. of the back of the helmet.
DW