Most conditions under which Pence would become President would make it nearly impossible for him to win. He would carry all of Trump's baggage, and some of Trump's supporters would likely stay home with him at the top of the ticket. Bernie would probably win with Obama's 2012 map + NE-02, and maybe AZ/NC, though those are tougher states for him, admittedly, and he might lose Iowa.
I don't see him holding NV, and FL is always unpredictable. I also don't know how OH would do. It would be interesting if there was a centrist independent bid. That could cost either party some states.
NV's competitiveness is overrated (it's at least a Lean D state, IMO), and Bernie would do better in rural NV and probably Washoe than Clinton, and would probably get enough of a margin in Clark to win the state. While FL is more of a question mark, I think his weakness there is somewhat overstated. In the end, most FL Democrats would probably come home for him, and it would come down to turnout, as it always does.