Diagram illustrating the window of opportunity for the production of hard ionizing radiation in our single-star wind-stripping scenario (highlighted with purple shading). The blue- and red-hatched regions indicate where dense WR winds and evolution into cool SGs would prevent the production of hard ionizing radiation, respectively. The values for minimum WR luminosity (blue line) are taken from Shenar et al. (2020) and the He star and WR transition in orange are the points where Sander & Vink (2020) predict the onset of multiple scattering (η = 1), below which winds are expected to be weak.