Agreed. I've installed a fourth battery to run all my electronics and livewell pumps. Not really necessary but piece of mind that I won't run down my starting battery after a long day on the water with everything running.
Or...do like Ranger does now and install a "jump box" that allows you to switch over to your TM batts for starting if you run down you starting battery. I think Mini has 5 batts in his boat. You can also go to a larger group size starting battery.