The question is: how important is it that you be in FRA on Tues am? There's nothing wrong w/letting the GA know you'd be willing to take the bump and if they need you to do it, they'll ask you. I suppose there's the potential to re-book you DFW-ORD-FRA and still enable a Tues. arrival (oops - no there's not according to above post)

As for how "uncomfortable" you'll be - its a 777 so it will have IFE which makes Y much more bearable as will an aisle seat.

Bon voyage.....