Your setup is different than mine and there is support where I could mount a swingarm on an a reinforced panel section. However, because of the differences, you really will need to pull the unit first. I can't tell looking at your pic if your have a reinforced panel on which to mount the swingarm.
Pull off the two vertical side covers, which are connected to the unit through clips. Its tight but gently use a small flat bladed screwdriver to wedge them out. Be careful not to mar the paneling. Next, you will have 6 screws that need to be removed that hold the base unit in place. The unit slides out fairly easy so an extra hand can help hold it as its both heavy and connected, of course. This will give you room enough to shine a light into the cavity to see what your cabinet has inside.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD