All you can do is try. But I suspect you have some foreign material between the bead and the rim that is causing the leak. As you drive, the tire flexes. And it's that flex that causes the intermittent opening between the rim and the bead. If I'm right about bad seal, over-pressure might work at first. But only until the air pressure goes down again. Then you're back to square one.
I'm pretty sure you're gonna have to clean the rim and the bead. But doing so when the leak and the valve stem are on opposite sides will be tricky. Only thing I can suggest is to rig up some kind of air hose to make a very long valve stem extension. Run the extension through the hub hole in the center of the rim. That way you can break the bead and clean the leaking side, but still be able to re-seat the tire against the rim with air pressure when you're done.
//greg//