How about a provisional load sheet with sector fuel (sword or whatever your name for the plog is) and give the guy an accurate underload?
We can add 800kgs and LMC it without a new loadsheet.
It's still giving his lateship the final say, but unless it's bad weather then 800kg extra for a 319 covers quite a lot of contingencys.(spelling?)
Top him off (or top him if you'd rather
) wave away the fueller and point and point out how you've saved the day against all odds, again