I bought this one, I have several Mercedes (always buy used!!!) and special tools pay off for me.
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I would definitely NOT reinstall the bolt with an impact driver, you'll be putting a lot of percussive force through the bearings, chain, guides, etc., removal maybe ok, but I'd never install a crank bolt with one.
For the torque angle, I use an old school dial gauge like this one, maybe someday I'll break down and buy a digital torque wrench with the angle gauge built in!
ZKTOOL 1/2" magnetic Torque Angle Meter, A New Type Of Drive torque angle gauge, Including 360°Adjustable 1/2" Drive Torque Meter, 16-Inch Magnetic Soft Rod, And Powerful Clamping Arm. - - Amazon.com