Do I need some kind of rear heat?

Hi everybody - I'm looking at a few 2014 Sprinters right now, and depending on where in the country I'm looking, some have different heat options:

Some have base heat (nothing additional).

Some have the front aux heater only (which, if I understand correctly, can also serve as a kind of block heater to warm the coolant and assist the glow plugs in providing easier starting).

Some have rear auxiliary heat only (for the passenger compartment I'm guessing).

Some have both heat options.

The van is going to be used in Wisconsin and parked outdoors, and it gets pretty cold here in the winter time. A lot of the vans I'm looking at in the southern US have no additional options installed. A few I'm looking at have one or the other, but I've not yet seen one with both.

Can you add heating options after purchase, or is that major $$ and better to purchase already installed? Do I really need rear heat? What I can I make sure the van has on it to ensure better winter starting?

Thanks for the help!

Why not call the sprinter dealer in Milwaukee and see what they recommend?
I bought my van from them last year and drove it back to San Diego....it has an aux heater of some sort, never used it: it doesn't work unless under 39* degrees, and that most likely isn't going to happen here.
Sprinter Waukesha on the outskirts of Milwaukee.
JR was the sprinter sales guy name.
They most likely order vans that meet the needs of the Wisconsin market.