All 3 should consider Trump for VP for the same reason that Biden is VP. What enemy foreign or domestic would want to knock off the POTUS knowing who would step up?
Whatever one may think of Trump, and I personally think he's a joke candidate, the one thing we can be sure of is that he would never be happy playing second fiddle. There is no way he'd be willing to spend a minimum of 4 years going to post office openings and funerals. Trump is too much a showboat for the job of VP which largely entails being quiet behind the scenes. So no, Trump will never be considered for VP by anyone.
As to the other 3, I like them all just fine. Carly less so simply cause I haven't heard enough from her to pass judgment. Walker has real accomplishments battling unions and winning. Cruz is a genuine conservative steeped in conservative thought and ideology right to his core.
Carly Fiorina as Vice President
Department of Foreign Affairs, (change the name back.) - Ted Cruz
Department of Justice - Trey Gowdy
Department of Treasury – Steve Forbes
Department of War, (change the name back.) - LTC. West
Department of Interior, (includes former Agriculture, and Transportation functions) - Gov. Palin
Department of Labor and Commerce (includes former Energy legitimate functions) – Gov. Walker
Department of Health and Human Services, (includes VA functions) – Doctor Benjamin Carson
Department of Homeland Security – Gov. Martinez
Department of Education - ELIMINATE
Department of Housing and Urban Development – ELIMINATE