Alright, thanks everyone who replied, but as this is not truly my vehicle, and it is a difficult fix as I have been told, I believe I may put this off for a while, and get back to it in time....
That being said, it IS a large hole in the bottom of the engine, and I am reluctant to leave it sitting like that for fear that stuff will get up into the engine
I have tried covering the hole with duck tape, but it does not seem to hold, and falls right off after walking away from the vehicle, so for now, I have just stuffed an old rag up into the hole.
My question now becomes, is this a decent long term solution, or do I need to do more prep before leaving this vehicle sitting for a month or two??
Again, I KNOW I am not a Mercedes specialist, and would appreciate some good, straightforward answers here, and NOT to be attacked for lack of knowledge.