overall height is only 1 factor
I would hazard that she has a short inseam.
My suggestion, ask one of the Spyder Accessory companies (i.e. the sponsors) to see if they can fabricate new, longer brake and shift levers. Then you can get some rubber mat material (like they use in horse trailers) and add layers in 1/2 increments to the floorboards. Hold them on with a screw or 2 or quality nylon zip-ties. personally I would use screws, or potentially fabricate a bolt-on piece that is hinged to the floorboard mount and can fold down and up like the passenger floorboards fold.
I have a friend (Harley trike rider) that had a newer longer shift lever fabricated because of issues he has with his feet
She might want to try different boots
I have a 2011 RT and I am 5'0 I have no problem reaching the pedals. it might be the handle bars? If she is leaning to far forward then it will throw off her foot positioning. Also I noticed a big difference when I got my Ultimate seat I can adj the driver back rest to sit closer up and I am directly over the pegs. These are just some options. I ride my RT all over with no issues. Tell her keep trying she can do it !