OXCE already uses pseudo-battlescape for deployment (Crew → Preview) and to walk the base (right-click on the Access Lift).
This could be much the same, via right click on a facility and constrained to one big room with some dummies and standard flimsy cover. But with real turns and resource regeneration, rather than infinite TU/energy, to evaluate how this will work in a real mission. It would have to discard some or all changes, however, especially if using "hostile" dummies.