I see only one AF flight from Orly, and starting only from April 20th. It leaves at 7:25 AM and is AF metal with business class on board. But as OP says he/she booked this for Easter holidays, this may be too late. Also, as OP is from Belgium, an overnight may be required as the flight leaves very early. Otherwise, it looks like some of the flights CDG-TUN are still operated on AF-metal, according to EF. But it is mostly the A319 by 8R (Amelia), with on board 1 class, 144 seats, 24 rows of 6 seats across. I am sure that you will have some of the perks of booked business class, like lounge and luggage, but on board i doubt that there is different catering and, as you mentioned yourself, no empty middle seat. You have not many alternatives. But one of them is TunisAir: they often use a widebody from ORY to TUN on TU719 at 12:40