I'd think that placing them in a scale-ish location would be fine... just look at some pics or decal guides (from plastic model decal sets) of real jets to get an idea of where they should be located. Some examples -

BEWARE OF BLAST - On the rear of the booms, or on fuse ahead of the turbine

NO STEP - On wing root or LE near fuse

RESCUE OPPOSITE SIDE - on one side of fuse, below canopy, about 1/2 way up, usually on the right side

FILLER WELL JP-4 - Upper edge or side of fuse behind cockpit, or out 1/3 span at high point of wing (fuel filler placard)

NO PUSH - On the top rear edge of flaps or ailerons, or rudders

RESCUE - On fuse opposite side of the "rescue opposite side"

Have fun!

Barry