Sorry I didn't mean to run anyone off.
Don't worry about it, it gave me a little time to see what my options might be.
Option one would be to multiclass rogue for a level, meaning stealth, disable device, trapfinding and 1d6 sneak attack tacked onto the eidolon form. Too bad Pathfinder trapfinding's not as good as its 3.5 counterpart. With the half-elf favored class alternative when using a summoner, the loss of one evolution point wouldn't be noticed. Wouldn't be able to dimension-door once per day and have one less second level casting, but oh well.
Alternatively, since we're allowed two traits "Conspiracy Hunter" gives stealth as a class skill and "Vagabond Child" gives disable device. I think these two would probably be easy to spin into a background together, (short version, began to suspect the people she was left in the care of were conspiring to use her for political gain due to her lineage, ran away or... something, proper details yet to be written out).
Ooooor... I could just be a rogue or a ranger. A
lot less interesting, but easier than the shenanigans listed above.