I think you'll be fine. I haven't heard of elevation impeding implantation.
When I was 30 weeks pregnant, I was in a wedding in the mountains in CO (about 9k). I live at sea level. My doctor didn't have any concerns. I think the main concern for pregnancy is making sure you are hydrated.
Now that doesn't really relate to implantation, but I can't imagine it would be that bad. I would go for it.