Re MrMike's spreadsheet - I believe that the calculation can be carried out just by measuring the distance between the mainwheels and the nosewheel. Using his data:

----------------------------------0---------------------------0
........................................262.4<-------------25------------>
.................................................2 70.4<---------x----------->

Moment about the CG = moment about the mains

270.4x = 262.4*25
x = 264.4*25/270.4
CG = 24.26

So CG is 24.26inches behind nosewheel or as given by MrMike 44.26 from nose of the aircraft