I thought about a Braille battery for the new project, but decided to move the existing lead-acid unit to the trunk and put the weight to good use.
But adding a switch for it doesn't bug me.

As for driver weight: I've always been skinny - usually 160 lbs - so it's always seemed a curiosity to me when big round guys are worrying about car weight.
I'm not being judgemental, it's just something I've never personally had, though my younger brother did get the "weight gene".
But everyone I've known who's returned to a more proportionate weight has felt & performed better.