Your odds of doing ETPS without being at-least employed by the military are sufficiently slim that I'd discount them.
There is NTPS (ww.ntps.com) at Mojave which is a civil-run school and as well respected as any of the military schools; it's also far cheaper. However, it's still expensive and you're likely to need at-least a major employer behind you, there's not a great deal of chance of self-funding through anything other than one or two of their shorter specialist courses.
I must admit that I can't quite see your logic - you want to do an aero-eng degree, so presumably are interested in Engineering. You want to be a pilot - equally nothing wrong with that. But, being an FTE is about flying in test aircraft, and both TPs and FTEs are deeply and intimately involved with the planning and analysis of the testing, as well as the conduct. Or in other words, I can't quite see what you've got against being an FTE, it's not (unless you work in an area testing single seaters only - which is pretty rare) incompatible with flying, please don't think that FTE is a ground job or doesn't involve an intimate relationship with aeroplanes. Equally don't think that being a TP gets you off the deep technical bits (or not being a good TP anyway).
Basically there are three routes to Test Pilot.
- Become a very experienced pilot then persuade somebody to train you in flight testing, or
- Become a well qualified and very experienced aeronautical engineer and also gain sufficient flying experience, or
- Go in as a junior pilot with a company who conduct test flying, and learn on the job (does anybody still do this?, I'm not sure).
But, I'm afraid that your 12 years+ is a sensible minimum to become a TP, by any of these routes. There isn't a quick route in, and so far as I'm aware never has been (nor I suspect would you find many people in the industry arguing that there should be either).
G