I replaced the charger in my converter/fuse panel by removing the converter and rewiring the fuse panel inputs from a different one, mounted in the same space. I don't know how similar mine is to yours. I used a charger/inverter with transfer switch (Magnum 612). The charger does not hum. Sadly, the inverter hums badly and cannot be left on at night.
They really should publish their noise figures, if they are going to be that loud.
On mine, I could pull the charger out from under the fuse panel from the front access - but I also had access to the top.