We study the morphological and structural properties of the host galaxies associated with 57 optically-selected luminous type 2 AGN at $zsim$0.3-0.4: 16 high-luminosity Seyfert 2 (HLSy2, 8.0$le$log($L_{rm [OIII]}/L_{odot})<$8.3) and 41 obscured quasars (QSO2, log($L_{rm [OIII]}/L_{odot})ge$8.3). With this work, the total number of QSO2 at $z<1$ with parametrized galaxies increases from $sim$35 to 76. Our analysis is based on HST WFPC2 and ACS images that we fit with {sc GALFIT}. HLSy2 and QSO2 show a wide diversity of galaxy hosts. The main difference lies in the higher incidence of highly-disturbed systems among QSO2. This is consistent with a scenario in which galaxy interactions are the dominant mechanism triggering nuclear activity at the highest AGN power. There is a strong dependence of galaxy properties with AGN power (assuming $L_ {rm [OIII]}$ is an adequate proxy). The relative contribution of the spheroidal component to the total galaxy light (B/T) increases with $L_ {rm [OIII]}$. While systems dominated by the spheoridal component spread across the total range of $L_ {rm [OIII]}$, most disk-dominated galaxies concentrate at log($L_{rm [OIII]}/L_{odot})<$8.6. This is expected if more powerful AGN are powered by more massive black holes which are hosted by more massive bulges or spheroids. The average galaxy sizes ($langle r_{rm e} rangle$) are 5.0$pm$1.5 kpc for HLSy2 and 3.9$pm$0.6 kpc for HLSy2 and QSO2 respectively. These are significantly smaller than those found for QSO1 and narrow line radio galaxies at similar $z$. We put the results of our work in context of related studies of AGN with quasar-like luminosities.
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