I’ll echo the ‘go bigger earlier’ suggestions- last year I got enough mileage in on Christmas Eve to almost make up for Christmas day, but after that I generally aimed for 40miles a day (I did all bar one of the rides on MTB or cross bike). That combined with a steady build up of late nights meant I was getting pretty tired and seriously losing the will by the end.
Getting a few extra miles in when I was out would have given me more of a chance for a ‘rest/lie in day’ somewhere if needed.
Also, don’t make the new year’s Day ride a very muddy singlespeed loop where you have to take the long way home to hit mileage. Really depressing, that!