The second fuel tank has been mounted, now make the hoses and connections.
1. cap
the preparation was such that this second tank opening looks the same as the cap of the main tank:
And this is how it looks from underneath:
It took some connections, but it is really good.
Under the chair it looks like so:
And the output of the tank is as follows:
In the middle the float for fuel level, also the suction and the top of the picture, the electric three-way valve.
I have ordered over the internet (AliExpress)
(indicate that it should be 12 volts version, I forgot so I got the 24V version, I still had to build in a DC-DC power booster)
This is how it is connected (on the right, the input for the rear fuel tank, to the left of the entrance to the front tank and in the middle the connection to the primary fuel pump).
On my dashboard I have placed a double changeover switch so that when I switch on the front tank, the level meter of the front tank is also switched on.
And best of all, it all works!