The Fit is high profile with a nice wide side. Lots of area for the wind to push on. My take FWIW is doing the band-aide fixes will have little effect.

To the OP, take your wife out on the road & help her learn how the car handles. I think the biggest problem here is she lacks confidence in how her Fit handles. My wife lacked confidence too. I took her to a few auto-x's & she became pretty good. She graduated to an SCCA national racing license & Pro Rally license holder & competitor. Be careful your wife may want to have a race car. ;-)

 

There's a difference between a light and twitchy feel from the steering, and excessive body roll from crosswind, even though you can feel both at the same time. Wider and stickier tires can improve the steering feel, by causing more friction when they scrub around the steering axis.

If you're going to stick with the stock LX wheels, I'd be looking at something like the Yokohama S Drive, partly because I've run several sets on a different car with good grip and steering feel, and partly because in 205/55/15, there aren't too many choices.

As far as the body roll, you can reduce it with a rear sway bar or stiffer springs. The springs also come with a harsher ride, so if it's not for someone who likes to feel they're driving a race car, I'd stick with the sway bar. It won't eliminate body roll, but it will help somewhat, improve the balance in corners, and it's relatively cheap.

 

 

I guess that's why I don't think the fit is that squirrelly either. My other other vehicle is a SV650.

 

Triumph Sprint here, and a CBR 929.