The second and third versions are both designed with HW Squads in mind. For both of these the foamcard is glued on externally, leaving enough space within for three HW Team bases. If the foamcard were applied internally, there just would not be enough room. Anyway, one is modelled to allow the HW Squad to have one gun of the Heavy Weapon Squad pointing out to cover most of the approaches to the bunker See Figs. 4 & 5. To be honest, I am not sure how LOS works in the current incarnation of 40K, so this might not be that helpful. But if that is so, then the third iteration is the one you want. I have carved out the front of the bunker, creating a "vision slit" which gives the three HW bases excellent forward LOS and pretty good side ones, too. If you have enemy coming at you from the font and simultaneously sweeping around your sides, this is the version you want to give your HW Squad the best protection while allowing the best field of fire. See Figs 6-9.
Stay tuned for more terrain updates, folks!