Hm! I'll look at my E30 if my daughter ever brings it around again.
It sounds to me that a directly-mounted reservoir would be a plus, having had to deal with resurrecting a 2002 where the braided blue lines had disintegrated.
In that case I was the driver of the towed 2002 over a significant hill and distance. Long story, full of humor and horror. End of the brakeless tow was up an 800-foot tall ridge to my place. I figured if the rope broke (again) on the climb, I would roll back into someone's driveway. If someone was right behind me, oh well...