I don’t think that the oil filling process is difficult, just messy.
Of course I’d like to work with standard parts, but so far I couldn’t find something matching out of the box.
I’m afraid there will be no alternative than to produce such an adapter by ourselves.
Unfortunately I don’t own a big machine park, sawing and filing has to be done manually.
But 10 mm Aluminium “sheet” - which could be the base material - isn’t that hard to handle.
Not really, but I’m talented in everything mechanical - that’s what people are telling me.
Special perhaps my mistrust… 
Let me tell you a story regarding this:
Back then I’ve asked Shimano (German and Austrian department) if it’s suitable to run their calipers in reverse.
At their first messages the said yes, no problem.
But the other day both Shimano departments contacted me again and told me not to do - note well; without giving a logical (technical) explanation!
Don’t get me wrong; I do respect security concerns, but I also want to understand them.
So…
A while later I stumbled upon the rear brake of the IF Move;
this is a reversed caliper without any doubt:
That means one can run a (I believe these are Avid?) caliper in reverse, but not a Shimano caliper?
What do you think?