Atmega328P-AU running on 3 C cells

I'm going to implement an Atmega328P-AU, the SMD variant, in my project. I will be loading the boot loader on it. If I choose "Arduino Pro or Pro Mini (5V, 16Mhz) Atmega328" under BOARD when I load the boot loader, that will work for the SMD, correct?
I'm wanting to power it off of 3 C cell batteries. I think the min/max range of typical alkaline batteries are 1.58 to 1.25. So will my chip have a BOD, and is it set low enough that is won't cut out on me? My batteries will be at 3.75 volts before there pretty dead.
I've read this:

"Arduino Unos are set for the 2.7V level."

Is that what my chip will have if I burn that boot loader I mentioned on it?
thanks,
(I won't be using any kind of regulator, because I'm needing to get super low quiescent current for this project)

I've read this:

Wher and in what context? A UNO works off 5V. So I suspect it is wrong.
There is no difference between a SMD and a through hole device they are both the same inside.

SouthernAtHeart:
I'm going to implement an Atmega328P-AU, the SMD variant, in my project. I will be loading the boot loader on it. If I choose "Arduino Pro or Pro Mini (5V, 16Mhz) Atmega328" under BOARD when I load the boot loader, that will work for the SMD, correct?

Yes that will work. So will choosing "Uno", as Mike said the MCU is identical except for physical packaging. The actual bootloader will be different, Uno uses Optiboot. But they both work.

I've read this:

"Arduino Unos are set for the 2.7V level."

Wherever that was, it is correct. Both Uno and Pro/Pro Mini use the 2.7V BOD setting. Of course the other settings could be chosen as well (1.8V, 4.3V, or disabled).

Wherever that was, it is correct. Both Uno and Pro/Pro Mini use the 2.7V BOD setting. Of course the other settings could be chosen as well (1.8V, 4.3V, or disabled).

2.7 should be fine for me since I'm using 3 C batteries. I'll replace them before they get that low.