Keep your bilge clean and oil-free to protect floors
If your engine bay bilge is dirty and full of oily water why not devote a couple of sunny days to deal with it. It will then be far easier to find dropped nuts, bolts and tools. It will also help prevent oily footprints being trodden into the boat.
Lay a white bilge blanket on any oily water to absorb as much oil as possible. Grey ones absorb water as well. Some people use disposable nappies to absorb the water but they can and do burst if not carefully handled.
Pump or sponge the remaining water, oil and muck out and spray the whole area with engine cleaner or degreaser. Agitate with brushes, adding more spray as required then rinse off with water and more sponging. When the area is clean allow it to dry, abrade and degrease the hull surfaces and then apply a suitable paint system.