Rather than mess with the hard morning start thread, I wanted to respond to old-timer's opinion that a battery cutoff switch isn't necessary or advisable. I have enjoyed your analytical approach to problems but in this case my real world experience trumps stated current draw on an opti pro.
With a grp 31agm in good shape my battery charge would be lower than 70 percent in two weeks of sitting.
Before realizing the extent of draw I experienced two ruined batteries when the storage facility didn't charge as asked over winter.
After installation of switch... No draw and no problems. Granted a switch could fail but the fix is an easy do. Just my 3 cents