It's a promising and ambitious project. But it is very dangerous to say the least. Although we know a lot about Mars and we'll probably learn even more in the coming years, sending a manned mission is a completely different story. Tests need to be made and numerous things need to be taken into account.
However, the idea of something such as dummies is not very viable, at least from my perspective. It would work if we were to see if man can survive in space or if man can walk on the moon. But with the distance between us and Mars and the possibility of a long stay there, dummies cannot be relied upon. In such situations, what is needed is the human brain and what it can accomplish under tough circumstances. There are just too many possibilities ans situations for a dummy to produce reliable results, not to mention the extra expenses.
Preparations and precautions can be made and taken. But if mankind goes to Mars, it's gonna be a trip to the unknown, the most dangerous thing we have done until now. No kind of test is enough and there is no guarantee of success. Yes, tests will help, but only to a small extent. The rest is up to the ones brave enough to attempt it.