On line source for Lifeline batteries?

That is what I am shooting for, I am a contractor and work at some remote sites. It will be nice to have a small microwave and fridge on my work truck. Speaking of cold temperatures would it be a good idea to add some heat mats for the batteries, I will be using the system all winter regular 30 degrees and down to the teens.

I got ahold of Powerstride Batteries and they have the 8Ds for $699.00 plus free shipping and they drop ship direct from Concorde so they should be fresh batteries, I am getting them ordered. Now I need to find a good place to buy the Outback inverter.