It's an interesting problem. I like the bilingual signs myself, and I like the Gaelic names on the OS maps - once you know your "hillwalking Gaelic" (great term, BTW) it helps you understand the locations you are in because many of them are descriptive.
Background: My Grandparents were native speakers and were thrashed at school for speaking the language. My parents understood the language but did not speak it much. I was raised speaking English and taught Latin and French at school, but not allowed to take Gaelic. My daughter has chosen it a language to learn in school instead of say French.
I went to school in a Gaelic speaking area (Sth Uist) when I was wee, and kids were told off for speaking Gaelic in the schoolyard (this was a long time ago), but I think by then it was because it was felt they would be disadvantaged if they didn't perfect their English by speaking it as much as possible.
Now Gaelic is recognised by law as an equal language to English by the Scottish parliament. The bilingual signs are part of the measures to implement this, but they seem to outrage a very vocal minority.
What the Welsh have done to save their culture is inspiring.