It's a long time since we overnighted at Portobello but it was our regular overnight on the way North or South. Never saw any bother with the motorhomes overnighting. The worst aspect was Karaoke night at the Pub a few yards away. Whatever talents the Scots have, singing is not one of them.
In later times I got my revenge on the Council by overnighting in the Haddington Council car park instead. On a Saturday night it was even better than Portobello. 24 hour toilet, fish and chips and short walk to supermarket.