Agreed Graphite Ghost. I believe I said connect in series with the battery ground cable which is negative. I am not familiar with the 3.2L starter motor power consumption specs. The switch shown can handle 20amps continuous and 125-amp spikes (1.5 KW).
Many of the idle operation power consumption issues cited are real but diagnosing some as being the potential cause for battery drain could be a wasted exercise. This is based on my personal belief that the quality and durability of some of today's batteries are not what they are advertised to be. I recently replaced a 2-year-old NAPA battery that would not hold a charge for more than a week. This battery was continuously maintained with a tender and never exposed to severe cold temperatures. I replaced it with an Interstate and no longer experience any failure related issues.