I did it last year, it was an absolute beast, at some points of the ride i wanted to curl up on the side of the road and phone for help.
But that was a pretty insane course (and I think i did the easier of the two), this year's looks a lot easier, I think most will finish within the time limit
Don't spend 4 weeks boozing your way around Slovenia, Czech Republic, Germany and France before embarking on the ride.
Put it more or less at the start of your holiday, suggest arriving a week before for a week of cycling to get warmed up, then doing the ride, then eating/drinking your way around europe.
The ride is really well organised with well stocked food stops, route markers, great event village and everything they could possibly think of.
Will be the experience of a lifetime - I am very jealous