BTW, how do you do an overhead join when approaching the airfield from the deadside of the circuit?
I wouldn't. I'd join from the deadside - same as OHJ without the flying over, turning, flying back and descending part.......There is NO reason to join overhead if you know the layout, runway in use, wind, etc.....you just lengthen the time of possible conflicts with other aeroplanes, and irritate the neighbours due to longer time in the air.