Wow, some people can be quite judgemental around here... It sounds like your goal is to REDUCE stress, not put her through something she is not capable of. DD has been through testing before and not once was she stressed over it. Mainly because I explained to her that 1. it wasn't a big deal either way how she did 2. there would be questions she wouldn't know answers to, but that was ok and to choose the best answer she could think of 3. this wasn't a test you can fail, only do well in 4. we would have something fun to do after that test.
Some tests can't be avoided, if you want your child's level of "giftedness" (wether IQ or school smarts) assessed. It's the only way to qualify for certain educational opportunities. I can understand that you want your DD to qualify for an educational program because of the shape of public schools. Our districts is in the top 3% in this country, but it still isn't perfect or provide extra services for gifted children the way they should. I hope your daughter does well.