Limiting 14V current to 50A
I have no idea what a "powerful charge source" or a "very large depleted bank of low resistance / high acceptance rate chemistry" is, but...

For these currents, I'd use teamwork.

Using a DC-DC chip intended for LED drivers or battery charging applications, we can build a buck voltage-limited current source, say 5-10A at 14V.

Then we stack them in parallel. These could be purchased pre-built.

To get 50A in a single design, you are likely to need lots of paralleled MOSFETs... and a multiphase buck controller, high copper weight PCB... I'd use 4 phases.