I just tested it myself, but I don't seem to have the problem you mention..
True the blue bubble is nowhere to be seen, but you can accurately place the car and you can rotate the direction you want your car to point at using the right mouse button. Since that is still totally blind, you'll have to remember the standard direction of the car though.
There is a way to overcome your problem though!
When you press 's' you can save your replay. Use this feature to save replays that don't finish the track and/or those that start on other blocks than the start. Do this in the track editor, so open a track press enter and position the blue startbubble to start driving. Hit the save shortcut to save. Now you can open the replay in the replay editor or import the replay into the mediatracker.
It takes a few seconds more to do this, but you do have the blue startbubble so it's easier to position your car