Agree with comments about potential for trouble on the gate... I'm pretty sure I remember a nasty incident in the USA a number of years ago, it was a type (727?) with the APU in the wing root... they had trouble starting the APU, it eventually caught, torched quite badly (no real fire, no indication other than TGT spike) but of course the pax saw this seeming fireball out the window... result was a chaotic pax-initiated evac with the expected panic and numerous injuries.
Anyone else recall this incident?