The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300AU is still poorly constrained. While molecular line observations demonstrate the presence of disks with Keplerian rotation toward a handful of sources, others show no hints of rotation. Determining the structure on small scales (few 100AU) is crucial for understanding the physical and chemical evolution from cores to disks. To determine the presence and characteristics of compact, disk-like structures in deeply-embedded low-mass protostars. A related goal is to investigate how the derived structure affects the determination of gas-phase molecular abundances on hot-core scales. Two models of the emission, a Gaussian disk intensity distribution and a parametrized power-law disk model, are fitted to sub-arcsecond resolution interferometric continuum observations of five Class 0 sources, including one source with a confirmed Keplerian disk. Prior to fitting the models to the de-projected real visibilities, the estimated envelope from an independent model and any companion source are subtracted. For reference, a spherically symmetric single power-law envelope is fitted to the larger scale (~1000AU) emission and investigated further for one of the sources on smaller scales.