Steve,
Now that looks like a ton of work! Why not just pull the engine? To properly remove the front cover one must pull the upper oil pan I guess? I agree they are not easy to pull on the SL's but removing the subframe? Unless maybe it is one of those early crack prone subframes that were supposedly recalled.
Here's a tip, why don't you go ahead and do the engine mounts while you're in there!
__________________
Chas
Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL
Got a Euro

500SEC right now.