Like M(F)S, I'm also "in Flight Test" but not a TP or FTE. I have, however, been known to contribute to the overall Weight & Balance of an Experimental aircraft (as Self-Loading Ballast). This includes seeing parts of the Mid-West from some very extreme angles (never go along with an ex-F18 driver & an ex-Tornado jockey when they're trying to outdo each other in clearing a civil HUD for "Unusual Attitudes").
I started out doing a Student Apprenticeship in the Civilian Division of Scrugg's and was in the Avionics/Electrical Design office until it became VERY apparent that the UK Civil market was on its last legs. This led to 5 years at the Lazy B as a shopper where I found I was one of the few not to have worked for Scrugg's Military Division. Keeping this side of the pond, I joined Canabeer in their Avionics group (then smaller than most mod. shops). After they were given to Bombardair, I was in the RJ design group that, like all the older programmes, morphed over to the Flight Test group ("We're doing the Flight Test in Wichita, do you want to join us?"). Been doing FT in the Air Capital just about ever since - with timeouts for Learjet report writing, RJ Autopilot & HGS Certifications.
As I've said before, modern FT is a team sport with contributions from people in the air and on the ground - even more so with the growing importance of simulation & system integration before, during and after flight test.