I would not mind a solution to this problem. I have had one or two items slip in that crack. If my camper is tilted down slightly and I am not cautious about my washing in the sink, water has been known to run into that crack. For now, I just try and be careful.
I also notice, on cold mornings, a draft can be felt coming out of that crack. It is really just caused by warm heater air cooling in the crack and flowing down. I sit on the couch with my feet by the opening in the morning while I sip my coffee and often times put a towel along the side opening to stop the draft.
I would probably just put some sort of dam along the right side of the counter. It would stop water and keep items from falling in. I need to get some ideas at the hardware store.
Steve