The point raised about the increased fuel flow is quite valid and the FCOM figures simply highlight the fact that your fuel burn is going to go way up with all that extra drag hanging out. You will do your head in trying to remember how much burns increase in varying failure modes. While I would never say that something like that would not happen in real life, the most obvious place that it will occur is in the sim and the only way to deal with it is to set a power that maintains you close to the manouevring speed for the particular flap/slat configuration. Gear is zero lift drag and simply goes up exponentially with the speed. I would spend a few seconds looking at the fuel flow and the groundspeed (FF/groundspeed =KG/NM) and work out a specific ground range or KG/NM and multiply that by how far I had to go, plus a reasonable manoeuvring allowance. Add your fixed reserve and you will be able to see if fuel is a real issue. Hopefully it won't be but in the simulator scenario, the man who is assessing you will be able to say that the increased fuel burn was considered and either disregarded as not a factor or acted on. It's the real figures (fuel flow/groundspeed) that matter, not the FCOM ones and if you have a reliable method for working out how much fuel you will burn quickly, you will free up a lot of available brainpower for all the other considerations.