I am looking at the same spot on my 2010.
I have an auto start that draws only 80 ma but that kills the battery after a few 3-4 days. Vipper says I should start the car every 3 days. They even have something I can turn on every time I stop the car to make it crank up when it reads the voltage getting down to 11 or so.
I am not always aware that I will leave the car that long. I also may not remember to switch the voltage start on (and it is a multi step process).
Any how I have decided to install the viper on a second battery.
On my 2010 the spot you are pointing to already has some holes for mounting something so i will get the battery attached there.
I know I am not the only one with this auto start problem. I have heard now of people with GM, Honda and Toyota's dealing with this as well.
This is the specs of the stuff I plan to put in there. Your drain is probably more than mine... but I want it to go for a long time and if you are just running the fridge for a while it might work. Installing the smaller battery should be much easier and not get in the way latter.
The oem alternator puts out a max of 90 amps.
Batteries plus has this battery (agm should be able to handle the
deep cycle and can mount in any direction):
Power Sonic 12V 18AH AGM Battery W/ .250 Terminal - PS-12180F2
Power Sonic 12V 18AH AGM Battery W/ .250 Terminal - PS-12180F2 - Batteries Plus
Item number: PS-12180F2
Weight: 12.2500 lbs
18 ah at 50 ma I figure it should go for about : 328 hours (just shy of 14 days)
Size is 7"*7"*3" and weighs 12.25 lbs
They do not carry circuits though. So I found this 95 amp one (is
that enough/to much?) at Napa:
Battery Isolator, 95 Amp
NAPA AUTO PARTS
Part Number: BK 7821769
Product Line: Balkamp
Alternator Type : Multiple Vehicles Equipped w/ CS Series Alternators
& Nippondenso Or Sense Terminals
Contents : Installation Wire & Installation Instructions
Product Application : Multi-Battery Isolation For 1 Alternator & 2 Batteries
Features and Benefits:
Multi-Battery Isolators Eliminates Battery Drain When Two Or More
Battery Banks Are In Charging System, Designed To Exceed OE
Specifications, Solid-State Electronics Allows Each Battery To
Discharge & Charge According To Own Needs
More Efficient & Reliable Than Mechanical Or Solenoid Systems,
Available For Multiple Application Needs