You are right to be cautious and b789's post sets out the future in that if the keeper did not prevail at POPLA then they would be in for months if not years of chase-up letters implying everything up to being hung, drawn and quartered. If at any part of this process you lost track of them, then you could end up with a default judgment against you. DCB Legal's reluctance to pursue matters to the point of paying the 'trial' fee is well-known, 'no matter how badly' defended. BUT it must be defenced and once you've embarked on this course you must see it through, even if it takes a long time.
IMO, you could defend this at POPLA due to there being NO evidence (in the NTK) that the breach extended beyond the 'consideration' period. IMO, this plays to a defence against the Code of Practice - which POPLA MUST consider - as opposed to the legal procedural issue as to whether for the purposes of this type of breach it is necessary to give a period of parking beyond a simple moment in time. However, if the entrance/exit were covered by ANPR and this shows that the time on site was well beyond the 10-minute consideration period (and this was adduced in their evidence) then a POPLA assessor might infer that the car was parked for this period.