(I have a Garmin 705) Recently I changed the way I deal with controls and how far to the next one. On the map page of the Garmin, which I use to follow the purple line, I set Distance to destination as one of two data fields showing.
When I get the route sheet I work out how far it is from each control to the finish. So even if I got off route badly, the distance to the finish less the distance from the next control to the finish gives me how far to the next control.
(I don't program in all the controls - too much faff)
As you use GPXX on a 705, Jaded, there's one other thing you can experiment with. I've not tried this in practice (just thought of it) but it should work.
Once you've finalised your GPXX, do the download from BikeHike as normal and then add a "coursepoint" for each control / info control / selected places on route, giving each a symbol and short name. Download again, this time as a TCX (course). You could also set a value for your expected average speed at this point. Put the TCX file into Garmin\Courses.
When you do the event, set the TCX course file going simultaneously with the GPXX. (From the menu do Training -> Courses). You should then get turn by turn from the GPXX and notification of controls from the TCX. (As a backup, the TCX will also display the route independently of the GPXX and will beep "off course" if you ever missed a turn).
There are several data fields and a separate data page related specifically to courses (course pt distance, distance to crs and time to crs are three of the fields. See Settings -> Data Fields -> Courses). I think the distance to crs would show the distance to the next control and the time to crs would be an estimate based on the average speed you entered during the download. When you reach a coursepoint the unit beeps and displays the coursepoint name. (You could set the coursepoint just before the real point for some warning).
There is also a further data page that only shows when you are "following a course" and that contains a list of all the remaining coursepoints (hence list of remaining controls) with their distances and expected times. (Using a TCX this way is very similar to Garmin's original intention for this data page which is to show a "road book" containing, for instance, a list of cols, sprint points, feed stations on a race with their expected arrival times and distances. In fact, adding the coursepoints using BikeRouteToaster or Garmin MapSource gives a greater range of symbols than those offered via BikeHike).
Shaun