I've seen .rkt files provided by the manufacturer for their kits... OR has the ability to open, alter, and save .rkt files (as well as convert them to .ork files). I don't know if the short config Darkstar Jr is among them though.
[EDIT] I've downloaded the instructions took a very quick look at them, then deleted the forward body tube and switch band (as well as moved the parachute to the remaining airframe) and saved them. See the attached .ork below.