Thank you for your input. It is all very helpful.
The doubler set up does look very simple to accomplish and might be a good candidate for what I am trying to do, as long as it does not exceed 7 amps. Actually, I would prefer to keep this down to 1.5 or 2 amps (or even less) to prevent overheating the cells in the 300v battery pack assembly.
Though I do not speak the "tech" language well, I assure you that I do have actual pro working experience in handling high voltage, know precautions very well, and have the correct protective equipment.
This charger is being designed for very occasional maintenance and balancing of a Gen 1 Toyota Prius Hybrid NiMH battery assembly made up of 38 x 7.8v cells/modules.
Though the cars hybrid charging system does charge at a much higher amperage, I only need in the range of .65a to 2.5a to properly maintain this assembly. In the maintenance and balancing process, which entails charging and discharging, I do not require or desire the fast charge that the car's hybrid system does. A low amperage charge is best.
As long as the amperage is low and the process is well metered and monitored, as it will always be, there is no need for other equipment or accessories with which to protect the battery.
Here is a drawing of my upgraded idea for accomplishing the 300vdc charging current.
Wish I didn't need the 4 switch bank but I'm under the impression that in order for the capacitors to fully charge to a good 115v individually that I am going to have to prevent them from discharging into each other while they charging.
If I am wrong about that, it would be great. I'd love to avoid the complexities of putting those switches in.