The way I see it working is that <=9 players are on BLU doing what bots do. On the other hand, 1 player is Saxton Hale and will get not only a model switch, but some OP weapons to simulate VSH/FF2 Hale. Said user will get a bit of cash as well, in order to facilitate upgraded stats, canteens, or quicker respawns.
Whether Hale completes the wave successfully or not, one person on BLU gets to become Hale, old Hale joins the bots and has weps and model reset, and the process repeats again.