How to increase EV autonomy of a Gen 3 PHEV?

First of all the original Toyota EV autonomy of a Gen 3 PHEV of 22km is a joke. If I was commuting in this range I would use rather a bike. When I was younger I even run at these distances.
But at 79, having a Gen 3 PHEV in the garage and 7kWp as well as gas prices on the roof, I thought about adding Lithium LiFePO batteries in parallel, secured by a BMS. (Ex. 72 pcs of 32Ah in series, incl BMS with equalizing function)
Putting a second battery pack in parallel is nothing new to the Prius, the early model (some beta version) had already separate hybrid and PHEV batteries. (And probably separate BMS)
In fact nothing would happen since the battery ECU sees only a virtual battery pack with the same characteristics just a bit higher in capacity. Even the SOC is pretty much the same as charging and discharging are very similar. Instead of using LiFePO one can also opt for Li-Ion.
THere might be a transient phase when the two packs are first connected and equalizing current would flow from the higher voltage battery to the lower voltage battery. This can be managed by a current limiting circuit in order to prevent too much heat. (Here we are talking about 40W)
The price could be around 1000-1200 USD incl. the BMS and a high voltage high current contactor. A lot lower than swapping the Gen 3 for a Gen 4. Besides the increase in autonomy would be also higher than that of a Gen 4. (80km vs 45km)
I can also live with the Gen 3 limitation in the performance section. And I won't even bother the ICU to get warm unless on a Friday like many of the chatters suggested in another chat.
Anyone of you already made research on this subject?
I would appreciate constructive comments, real objections regarding the CAN messages that might cross such an undertaking.

 

Some of you might wonder why a european Prius owner is interested in Gen 3 plug-in autonomy.
It is very simple:
1. Putin has tought us not to leave decisions in energy matters to others. Germany has failed big-time! So I learned.
2. Fuel costs in Hungary today 1,93 USD for a QUART! Twice of the price a year ago. My retirement didn't increase
3. The Sun is still shining without any modesty, roof electricity is chinese but it works well
4. Resale of electricity is fortunately adventageous, my last years total invoice was 80 USD (For 10'000 kWh)

If I were a car manufacturer (which I am not) I would offer a plug-in hybrid car (No SUV!) in two versions:
1. Size small (S): with 10kW battery capacity enough for ~ 38 miles/62km in EV (50 Ah cells @200VDC, 80kg)
2. Size large (L): with 20 kW battery capacity enough for ~ 75 miles/125km in EV (100 Ah cells @200VDC, 160kg)
Anything else is size extra large (XL, XXL) where the hybrid traction with a smiling ICE takes over.

A plug-in hybrid is for users with S,L, and XL needs with only a one car garage.
Others can get a Tesla and a Porsche if they have enough change.
I wonder why Toyota is such a conservative and overly anxious company to offer seedless grapes to people who have perfectly functional digestive system.