I had a solid panel in front of the water heater winterizing valves. I had to either pull the drawer just above, and with ball-bearing slides, it was a pain to manipulate both stops just to get a bit more room. Plus, I couldn't avoid the silicon on the slides.
Alternatively, I had to pull the six screws on the panel.
After swapping the dinette set for theater seats ( https://pbase.com/brucemac/2015sunseekerseating
), I had two spare drawer faces, so I mounted one of those faces in the blank panel, as follows:
Door mounted in panel, ready for mounting in cabinet:
Back of panel showing the bracing for hinges and the latch:
Cabinet with closed door:
Fortunately, I had a matching door as far as the material & finish.
Your panel is probably stapled from behind. A door can be added if you can make one, or as others have mentioned, find one or have a cabinet shop make one if they'll take on such a small/tiny job.