Expected surface brightness profile of the BCG + ICL (solid coloured lines) and 3σ noise level (dashed lines) for a range of redshifts (z; upper panel), ICL fractions, (f_ICL; central panel), and halo masses (M_h; lower panel) varying with respect to our fiducial model where z = 0.3, f_ICL = 0.15, and  log₁₀ (M_h/M_⊙) = 14.7. Profiles are shown up to redshift 1.2, above which a cluster of this mass is not expected to exist within the area of the EWS (see Fig. 5, grey shaded region). The fiducial model is indicated by a thick line in each panel. Moreover, the black dotted line in each sub-figure is representative of the background noise level for the fiducial model. The noise level depends on the redshift of the cluster (see upper panel), but varies little for z>1.0. The radius to which ICL can be detected increases with f_ICL and M_h, while decreasing with redshift.