Observations show that the first galaxy clusters were already assembling by z ~ 2-3, earlier and more massive than predicted by standard cosmological models. Understanding how these dense environments affect star formation provides direct insight into how galaxies form and evolve. SPOTLESS (Searching for Protoclusters through Observations Tracing Luminous Extragalactic Sources Survey) examines whether dusty star-forming galaxies (DSFGs) can serve as signposts of protoclusters. We investigate two gravitationally lensed DSFGs, SDP.17b (z = 2.30) and HELMS-55 (z = 2.28), using deep Ks-band imaging from Gemini/Flamingos-2 together with Subaru/HSC and HST multi-band photometry. Photometric redshift analysis identifies at least 5 ± 2 and 15 ± 3 companion galaxies within 5.5 comoving Mpc, corresponding to overdensities significances of 0.2 ± 0.4 σ and 2.2 ± 0.6 σ, respectively. Based on lower-limit halo mass estimates, the HELMS-55 environment is expected to evolve into a present-day Fornax-type cluster. Stellar mass and star formation rate estimates indicate that most of HELMS-55's companion galaxies lie below the star-forming main sequence, suggesting early quenching. Based on this study of two DSFGs, our photometric analysis suggests that DSFGs can trace the outskirts of protoclusters or associated large-scale structures, although a larger sample is required to determine whether they consistently pinpoint dense cluster cores.