I honestly sympathies; I work globally, therefore I have little control over the computing environments that my hardware connects. In my experience of over 22 months with the Retina MacBook USB C with only Apple's own adaptors and dongle's is in the region of 80% successful, which I am sorry to say is unacceptable for professional usage.
I generally travel with two notebooks, which has resolved the issues on several occasions, equally I will not purchase a USB C only notebook as a primary tool, be it Apple or another provider, for obvious reasons; it simply comes across as unprofessional & embarrassing when Apple's finest is incapable of connecting to something as simple as a projector...
Many of the objectors simply don't want or are incapable of understanding other users needs, nor are they capable of visualising the magnitude of the problem. "err can I borrow your computer?" Just no absolutely, it instantly sends the wrong message, clients not going to sign off on a substantial technical contract, when you can't even manage your computing solution...