  We consider the Higgs sector in an extension of the MSSM involving an extra
U(1)' gauge symmetry and SM singlet U(1)' charged scalars, in which the
effective $\mu$ parameter is decoupled from the Z' mass. There are large
mixings between Higgs doublets and singlets, significantly affecting the Higgs
spectrum, production cross sections, decay modes, exclusion limits, and allowed
parameters ranges. Scalars considerably lighter than 114 GeV are allowed, and
the range $\tan \beta \sim 1$ is both allowed and theoretically favored. We
concentrate on the lighter (least model dependent) Higgs particles with
significant SU(2)-doublet components to their wave functions, for the case of
no explicit CP violation in the Higgs sector. We consider their spectra,
including the dominant radiative corrections to their masses in the large
$\tilde t$ mass limit; production cross sections and exclusion limits at LEP
and a future linear collider; and decay properties.
