I have a 2011 CRV that I tow. Spent $90 extra for a cut off switch when getting it prepared for towing. I use a Brake Buddy.
That said, the $90 was a waste of money. The radio fuse that the switch controls also cuts off the accessory jack. I had to rewire. I know you don't use a powered braking system but I went months without using the switch. I turned off the radio, made sure the fan was off and I would go 10+ hours with no issues.
My 2011 had very few miles on it when we bought it so I will assume the batt is "less used" than yours. Point is, go get a good battery and forget about everything else. Don't waste your time with a switch!