Eventually, I got the latest model of Sundowner, which is assembled of 2 parts.
It looks good from the top, but visually it floats 1 inch above its place (when looking from the side) which is not so good. Also, the inner design looks flimsy: 2 parts instead of 1 solid tray, flimsy plastic tongue on the front.

I did a little ride around the district. Found that it keeps me not planted (unlike the stock seat), and gives much space to move: backward to more beefy support, or onwards to the tank, where it is emptier than the stock seat.
Also, it provides a higher seating position. Maybe I will stop complaining about how this bike low

Now I have to test it with my wife on the pillion. Passenger's pillion is wider but shorter than the passenger's part of the stock seat. Current weather in UAE is effectively prohibitive for my wife to go out of air-conditioned space.

 

Id go for a mustang seat