I saw the other thread and considering the quite broad nature of the question, I thought the responses were very helpful to guide you to looking at the right places to find the leak.
To do it right the water pump needs to come out to replace it. It's a job that requires a little competency and expect to run into [at least minor] problems while doing so. It's one of those jobs that will have you cursing out mercedes, but once you've finished you'll be saying it wasn't really that bad and it would take you a quarter of the time next time you do it.
These hose don't usually go "bad" but can develop leaks so if you're looking for a temporary solution, I agree with workerunit and tighten/readjust/add clamps. Carefully "feel" the hose to see where the nipple ends. The nipple coming out of the head extends to within about a 1/4" of the outlet on the pump, so you should have enough room to set another clamp on the pump side of rusty one in your picture. There is a flare on the end of the pump outlet and that clamp usually rests right up against the flare, but that side is probably sealed okay. You also have enough hose on the head side of the rusty clamp that you might be able to add a clamp there as well. The nipple is pretty heavy gauge so I doubt it's rusted through, but it may be pitted. As said this is an ATTEMPT at a temporary solution. Since your leak is minor, this is probably all you'd need to get you by for a while.
As far as being able to put a new hose on without removing the pump, I'd say it's very doubtful and if possible it might totally depend on how much space there is between the nipple and the pump outlet, which, while it may vary some, it's usually only about a 1/4". I tried (for the hell of it) to do it when I did my head gasket and found that for all the trouble I was having to manage it (if it would have ultimately even been possible) I'd just a soon take the pump off. One of the big problems, even if you can get the hose on part way is that you'd need to slide it all the back onto one side or the other to get the hose fully on through the narrow gap and then slide it onto the other side. The problem is, the pump outlet is too short (and wider than the nipple side) to slide on that side first. The nipple is long enough but the intake manifold is too close to it to allow the hose to slide back much further than it is sitting right now.
I thought about cutting the nipple shorter when I had the head off to facilitate being able to do this later, but I concluded that these hoses almost never go bad and taking the pump off isn't that big a deal once you know how to do it. If they do develop a leak, readjusting/tightening the clamps should take care of it.
Just my opinions.

Edited to add: anthonyb is correct, the MB hose is somewhat thinner walled than the aftermarket hose (at least the ones I got). And you are likely to need a new belt tensioner, they're not a longevity part.