What technique do you use if you are doing a right circuit (you are in the left seat) when commencing the downwind turn to not lose sight of the runway?
Ask the guy in the right seat to keep an eye on it or let them fly the circuit.
You assume I was talking about a single pilot operation or that I sit in the left seat.
I only took point against the statement that you
will lose sight of the runway. Whilst this is true for some aircraft it is not the case in all situations.
If you think the circling approach will be marginal (due weather, terrain or aircraft perculiarities) change to the runway aligned approach or wait for conditions to improve/divert.
As for GPS/RNAV replacing all ground aids I hope not. The GPS procedures are good but have seen GPS units fail or do strange things, especially in heavy overcast or rain and icing (when you need it to work). When they fix these issues fine, until then leave some ground aids scattered around the countryside.