Driver's seat height safety problem

I am looking for solutions to a driver's seat height (2013 Prius 2) safety problem. The seat lowers adequately for me (6'2") but does not raise enough for my wife (5'3"). I have worked out the biometrics with string, tape, spirit levels, and lots of measurements. Basically, we need a 5.5" height adjustment range. The manual seat mechanism provides only 3" of the necessary adjustment. I will be borrowing a friends 2012 Prius 5 to see the the motorized driver's seat is any better. I've looked at automotive seat cushions (a'la tush cush) but I can't get any cushion compression data that will assure a stable (not wobbly), net 2.5" gain.
- This problem has to do with visibility. I have no problems with my eyeballs at 4" below the top of the visor. My wife has a terrible problem with visibility - she is unable to judge relative velocity and acceleration of other vehicles in the right hand lane - the so called "blind-spot" area. She can see them but cannot judge where they are relative to the car. We did some experiments (static) and the problem was highly mitigated when her eyeballs were elevated to the same 4" below the visor top (the test rig would not be safe (unstable) while driving). I have access to a couple of other prii and all are set to the 4" down point for their respective drivers. This is a safety issue and not one of comfort - as all the driver's seat cushion advertisement's target. Any suggestions?

 

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Raising the seat, in a permanent manner, doesn't help because I need the seat at the bottom of its current vertical range. We share the car and the driver's seat goes through two to three height cycles (max up, max down) per day.

My analysis (I am an engineer of the anecdotal data is;
- My wife claims no visibility problems with either the 2013 Camry or Accord. Which leads me to believe that the Prius's lack of wrap around windshield and wrap around rear window is a proximate mode of failure. She reports that the very thick roof support posts (fore and aft) create "blind spots". She says that she almost hit a bicyclist who was hidden by the front right support post.
- I am thinking of installing a plastic Fresnel lens on the right front "port" hole window. This will increase the forward visibility "beam" spread by 17 degrees and increase the downward "beam" spread to 37 degrees, net. Allowing curb visibility down to 2' of the car. But, that is a semi-related issue.
- Based on various posts, a Prius driver is much more dependent on the mirror system for rearward visibility. Also, the curvature of the passenger side mirror seems a bit more radical than other vehicles (I haven't measured the radius of curvature), and thus may be more distorted than usual.

In any case, the numerical data we collected allows my wife to more accurately place objects seen via the mirror system when she is elevated to where her eye level is 4" down from the stated reference point. This requires a seat height range of 5.5" to accommodate both of us. She reports that the 1" height gain (after compression) due to a seat cushion helps. I just need to find a suitable seat cushion that provides a net 2.5" of vertical gain. Does anybody know of a source?

Thanks.

 

It's primarily her car. It replaces her 1992 Honda Accord, which was stolen. I sold my Honda CRX a few years ago as I didn't use it. I've been retired for 15 years.

 

Thanks for the reference. There are no medical issues. I'll look into GHC resources - the main facility is just a few miles away. Current thought is to commission a local re-upholsterer to construct something suitable. After all, what is needed is just a thick, firm seat cushion that compresses to around 2.5".
The main problem is lack of information (thickness & firmness specifications) from the various manufacturers.

 

Thanks, looks very promising. The local trail (Burke-Gilman) passes by their warehouse. A local outlet couldn't be too far away. A fantastic price, especially if it works.

 

Have ordered:
Large Medium-FIRM Wellness Seat Cushion (Size: 18" x 14" x 1-3/4" to 3-1/2". Color: Black)
Sold by TravelMate
From Amazon. It should work for 160 lbs, but if it doesn't, I can replace some of the "furniture grade" foam with REI blue foam - a closed cell foam pad that doesn't compress much (1/2" for a sleeping pad). Should arrive in a week or two. Am a bit apprehensive, since, according to one write-up, it is inadequate for 200 lbs and I really want 2.5" of additional lift (5.5" total).
- I should have used "drivers booster cushion" as my search strategy.
- The 27 full up / down seat pumps with the manual adjustment 2 - 3 times per day is getting quite annoying but $4k is a lot to pay for power up/down drivers seat. The other differences between the 2 and 4 are of no interest.

Thank you all for your help. I will post the results.