then the load charts wont apply!
In general, there should be no problem, presuming min crew load only. Revised LDS takes care of the config change and one then just ignores all the non-fuel trim lines as being irrelevant for the purpose ..
Otherwise a simple back of a fag packet exercise for the local weight control chappie.
Dual FMC failure and you want to takeoff?
Indeed .. surely it gets closer to being a real aeroplane and we olde pharts would be inclined to have a go ?
Reminds me of a wonderful Oz aviation icon. When doing his DC9 endorsement (previous jet was a Meteor in Korea) he was doing it tough .. until the standby power session ... waltzed out of the box with a grin from ear to ear ... "just like a real aeroplane, mate !" and, having discovered that the beast's facade was just that .. had no problems thereafter.