Would like to hear your thoughts with regards to such factors (control column position, turn rate, bank angle, etc.)
If you are established in a balanced turn your control column should be level, so any displacement away from that requires rudder to prevent skidding or slipping.
With regards to trimming in a turn, the FCTM states words to the effect of that we should fly the aeroplane in trim at all times when workload permits. I would therefore be quite happy for someone to trim the rudder during a turn providing they don't distract themselves from flying accurately. Furthermore, whist it might only take 2 minutes to complete a full 180º turn at 15º AOB, should the PF become incapacitated during that early engine failure turn due to the stress, and say have a heart attack, the PM will have virtually no chance of recovering the situation, however if even some trim has been applied, then their chances have improved dramatically.
As an instructor on the B737, I teach to trim when you have the opportunity, if your capacity is reduced whilst maintaining V2 round an awkward EFP then don't compromise flying the aircraft to do it, but do it sooner rather than later.