Our fifth wheel electrical system is enclosed inside the front compartment, but I do remember the problems with corrosion on all of our travel trailers that had exposed electrical components such as your circuit breakers that were mounted on the front bulkhead.
Probably the most effective and easiest way to enclose your replacement circuit breakers is inside a "modified" waterproof box. You could drill holes in the box sides, route the wires through the holes, attach and connect the circuit breakers as they are now wired and then screw the waterproof lid on the box. Once the system is complete and working properly, just fill the drilled holes with silicone to reseal the entries for the wires. If you need access, just remove the lid.
Here's one such box, about 8" x 3.5" (L x W) that is about 2.5" high. It would hold the wiring and circuit breakers in a small, waterproof container that would prevent future corrosion. It's small, possibly hard to get the wires into, but the small size makes it less noticeable. There are other, larger boxes that would be a little easier to work with, but their size would make them more noticeable and maybe more prone to damage because of the size ????
Anyway, here's the link to the box.
https://www.amazon.com/Resistant-Ele...e+junction+box
You can find those circuit breakers at any RV service center or parts store, maybe at larger auto parts stores (NAPA) and online. Most are 30, 40 or 50 amp sizes.