I found a very informative post about using SharePoint Designer with the Oslo master page, but its only advice was to switch to the Seattle page temporarily. However, in doing so, I'm going to confuse a lot of my users who are accustomed to the Oslo look and feel; or, I'll have to do all my development work outside of business hours.
That post is over a year old. Has there been a fix for the Oslo/SPD bug since then, or am I going to have change my master page and work after-hours?