Rino

Your really putting way to much thought in to this. Be safe but you need to experiment with the setup you have. Jack the car up and place it on jack stands. Shake it and see if it seems stable. If it's stable, try jacking it up farther. I would not place the car on the highest position, it's like stepping on the top part of a ladder, just not advised. Take some time to learn your tool setup and work with it. Experiment without getting under the car and you will learn whats safe.
As shown in the picture above it is workable and safe.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car