Unfortunately there is no option to define the amount of dead fuel within the aircraft profile. The only way to do this right now is adding an additional w&b station including weight&arm of the unusable fuel. Reduce amount of max fuel capacity in the profile to usable & everything will be fine. Any plans to exclude dead fuel in future releases?

The empty weight of an aircraft includes unusable fuel as well as all other fluids required to operate the aircraft. The fuel gauges are required to read "zero" when all USABLE fuel is gone. So why don't you define the tank volume as the amount of usable fuel and include the weight of unusable fuel in the empty weight of the aircraft? That's how it is supposed to be done.

-- Chris.

Chris, do you have a definitive source for that?  The Weight and Centre of Gravity Schedule in front of me includes:
"The basic (empty) weight includes the weight of NIL gals unusable fuel and FULL oil" (plus a basic equipment list). 

I've done some Googling, and I won't bore you with the details, but in various sources (including various parts of FAA 8083) empty weight may or may not include oil, and "unusable fuel" included in basic empty weight may mean "The unusable fuel supply for each tank must be established as not less than the quanitty at which the first evidence of malfunctioning occurs under the most adverse fuel feed condition occuring under each intended operation and flight maneuver involving that tank."  Alternatively, unusable fuel is sometimes defined as the same as "undrainable fuel".  Or, as in the case I've been looking at, it may not be included at all.

The long and short of it: don't assume theoritical endurance figures allow for unusable fuel unless you've checked.