Inexpensive compressors are
Easy to make or buy:
I made a set to hold springs when compressed to hold them when lowering the jack while the car is on jackstands. Made them from 1/4" X 1" steel flat bar and with a torch bent one end in a U to accept the spring. The other end bent at right angles and drilled a hole so a 3/8" bolt would slide through easily. Made them about 2 1/2 " long and cost almost nothing. Have used them for over twenty years now and have been invaluable. Just use good grade 8 bolts with them.
To buy an inexpensive set go to NAPA/Genuine Parts as theirs have the forged hooks and safety retaining bolts
for less than $30.
The big pneumatic or V clamp with a bolt tightener are usually too big and cumbersome to fit a Mercedes.