10% plus or minus
My previous battery experience agrees with the figures of up to 14.4v charging, around 12.6v for a resting battery and dropping to 12.1v min under a light load – it’s just the way a 12 volt battery is made. 12.73 volts on a meter would be quite possible though, as electronics are built to a price and usually allow themselves 10% plus or minus. So this is well within range.
Everyone should carry jump leads and a thick tow rope of course (plus sand ladders and maybe a winch outside Europe) for self recovery and being helpful. I hesitate to mention it though, but as my original post suggested, if you camp alone then by using a ‘big switch’ charging circuit you don’t need a second vehicle as long as the leisure battery isn’t flat. You might wait all day for any passing traffic and that might be a donkey cart… It’s tough jump starting from a donkey..!
However you power it – enjoy your camping