The 6'5" could be problematic, but as a very white guy I've had very positive experiences by just acting like I belong (acting slightly bored by everything around me while secretly enjoying the new sights, avoiding stops at subway maps and the like, dressing the part, etc.).
Most places I've visited have at least enough white people for me to appear 'local poor expat', but I can see how being the only white or only really tall person throws a wrench into that approach.
While people do notice faces and thus skin tone, one more obvious identifier, besides height, is gait and walk cadence.
Most foreigners will walk a different way from locals and it's really noticeable.
But dress is really important. Locals will wear some locally available brands, foreigners typically will keep on wearing the same brands they wore back home.
All that said, being 6'5" where just about everyone else is at least 6" shorter is a pretty unavoidable distinguishable difference.
Most places I've visited have at least enough white people for me to appear 'local poor expat', but I can see how being the only white or only really tall person throws a wrench into that approach.