Hi you mentioned that the JSF'bs primary mission is going to be amphibious assault.
Amphibious assault is something infantry personnel do. A ship lands them at a certain place, the ramp comes down and out they go onto land. That's what amphibious means, they can move from water onto land.
See the opening few minutes of
Saving Private Ryan if you need further instruction on this.
Then isn't the best option for the v/tol variant is actually to do away with its stealth capability and use the internal weapons bays to increase range after all its a bit hard to launch a stealth plane off a huge ship that everyone is going to see.
There is no F-35B "VTOL" aircraft. What the F-35B is capable of is "STOVL" which means: "short take-off and vertical landing". What this means is that the F-35B aircraft takes off normally as any other aircraft does, but with a shorter take-off distance.
IF you need to know how aircraft take-off, then please visit your nearest airport and watch the aircraft take-off. That is what the F-35B does, however it's design allows it to do the same thing in a much shorter distance like for instance, the length of a ship...
It then lands back on said ship vertically. The reason it does so, is because the ship is not long enough, nor equipped with arresting gear to allow the aircraft to land in a more conventional manner.
It is also much lighter at the end of it's mission than it is at the start and the power of it's engine and lift fan allows it to land vertically (ie: straight down) to simplify the landing process. The F-35B therefore can operate from relatively small ships that are cheap enough for many nations to buy.
Bigger ships that allow a more conventional take-off and landing procedure are more expensive and few can afford them nowadays, those that can however are usually stronger more powerful navies.
What VTOL means is "vertical takeoff and landing". That is what helicopters do.
The F-35B is not a helicopter. You can tell this, because it doesn't have any rotors...