Wiggy and undetectable are two different things. I have never seen an undetectable full head weave. I have seen some really nice looking full head weaves that were not thick if that makes sense. The fact that a real part is not present is what makes them detectable. That being said, you have to think about why you are wearing the weave in the first place. Full head weaves protect 100% of your hair. If you are wearing weaves to grow your hair, they are probably the best way to go (or purchase a closure which also covers the whole head). I have worn full head weaves in the past but I did not like them. I have never used a closure piece because I don't know any stylist in Charlote who can do it properly. I have heard horror stories about the one place here who does it. I accept the fact that my leave out hair will most likely not grow as fast as my other hair and may potentially get damaged from the heat styling I do.
So again, you just have to think about why you are getting the weave in the first place and educate yourself on the consequences of your choices.