If you want to run Project Lambda you can install a different map sensor, change the settings and you wont need a voltage clamp or anything like that.
I used a Bosch 0281002437 - 3 bar sensor. Plugs straight in BUT the mounting is a little different (1 bolt vs 2). Changed the Slope to 65.1kPa offset to -6.3kPa. Runs like a dream! I know you might be a little way off that but just in case you need the info in future..
Good website for sensor specs:
MKS Autobusiness, special components for special needs - Products
As far as the turbo drain goes, so many people have done the rocker cover route and had no issues. I'm going that way, theres a giant drain passage on the lower-rear corner of the head which runs straight to the crankcase. No oil will squirt/splash up onto the rocker gear as the flow rate is so low. At worst the rocker cover gaskets might fail early due to the temp.
I'll take a pic of mine and post up asap for you.