I certainly understand the "working on you back" complaint. I hate doing clutch jobs so much that I actually pulled the engine on my 240D last time to replace the clutch. I have a walking beam down the middle of my shop with a chain hoist hanging on it, so I am better equipped to do it this way. That coupled with the fact that the 240D four cylinder is so quick to pull made me try it. I was done in five hours and spent virtually no time underneath. It has always taken me longer to do a clutch job on the same model from below.
To get past the space constraint problem you just need plenty of extensions, universal joints and patience.
So, it sounds like your research showed that your engine has a one piece rear main seal.