Forms of endorsement or policies other than that described in
Sec. 726.203 may be entered into by operators to insure their liability
under the Act. However, any form of endorsement or policy which
materially alters or attempts to materially alter an operator's
liability for the payment of any benefits under the Act shall be deemed
insufficient to discharge such operator's duties and responsibilities
as prescribed in part C of title IV of the Act. In any event, the
failure of an operator to obtain an adequate policy or contract of
insurance shall not affect such operator's liability for the payment of
any benefits for which he is determined liable.