How do I use cheap MPPT charge controllers for DC-DC conversion?

I have 24V transformer wired into mains. I wish to power 12V applications in the 60A range and will have a LOT of voltage drop in the line (0–8V) but the voltage drop won’t always be constant. How can I use an MPPT charge controller to accomplish this? I couldn’t find a cheap DC-DC converter able to and voltage regulators able to just converted excess voltage into massive amounts of heat.