Locatioon to install Invisibrake in Honda Fit 2013

I'm having the same issue and I'm thinking of creating a platform to be above the Invisibrake where a passenger could rest their feet. I think it'd be the simplest solution. You could make it out of wood with little legs that are a bit longer than the height of the Invisibrake.

Ditto on the "no spare room" comment. Honda managed to turn all of the common "nooks and crannys" into usable cabin space. I installed the US Gear brake system and spent a lot of hours brainstorming where to put things. I ended up with the actuator servo immediately behind the outer driver seat rail. It intrudes into the rear passenger space a bit, but being on the side of the footwell, it's a nit. Ditto on the motorcycle battery observation, but still running the original battery in a 2009 model.

The Fit has no spare room,but other than that, it is a great toad. I ended up getting an RVi2 Braking system which, BTW, works great in the Fit. Also added a battery charging system since I swear, the Fit battery was taken from a motorcycle.

You do have room under your front and rear seats. Under the front will compromise rear passenger leg/foot room and under the rear, it could hamper seat folding. You could always return the Invisabrake.