By the way, I realize you are trolling, but young pilots may read this thread and think it is ok to fly through a thunderstorm. DON'T DO IT.
I am not trolling I am disusing weather related problems that can occur during long distance flights, should one find a situation where you have to fly through a line of thunderstorms in a unpressurized airplane you will have to decide at what altitude you will fly through the system.
Telling young pilots " Don't do it " is fine, however they may one day be faced with such a decision.......so I see no problem discussing such an event.
Then you've done a poor job of flight planning.
One route where flight planning weather wise can be very difficult due to the distance involved is West Africa to South America, the ITCZ can be many hours from the departure airport and the weather at the ITCZ can change very rapidly.
So what do you do if you find the frontal zone very active and you are past your point of no return?
If however you find yourself in this situation, start a deviation around the line as soon as possible. If you deviate soon enough you should be able to get around the line without burning too much fuel.
So how do you determine if you can get around the front if you do not have weather radar and you have hundreds of miles to go to reach land?
I realize most flying today is done at high altitude in modern well equipped jets.....
....however there are still occasions where older aircraft are ferried trans oceanic and sometimes penetration of vast very active frontal systems can not be avoided.
....another wicked weather factory is in the Amazon region where the ITCZ can change very fast and once again weather information can be sketchy at times.
Anyhow, trolling was not my intention, I see nothing wrong with discussing what can go wrong and what one can do to mitigate the danger.