Assuming we're not talking about orbits in strongly curved space time, then I was always taught maintain current configuration, altitude and speed and roll into a 30° banked turn, referencing a position on the ground. I have in the past reported "orbit complete" to ATC on completion of the orbit, though dunno if its strictly nescessary.
Not too keen on them, I think they're handed out rather too liberally at some airports. Last time into a certain field I orbited three seperate times in the space of about 5 miles....
I agree though that it would be unfair to ask CheapAir 123 to "cancel IFR" just because they're visual, and no doubt their SOPs won't allow it anyway. I would also leave the circuit of an "uncontrolled" field rather than orbit..........
EA