I'm all in favor of equal rights and protection under the law for trans people, but an 8 year old trans? 8 year olds don't know anything about anything, let alone what gender they "should" be.
Teach the child that gender identity is a complicated issue, they can identify as whatever gender they please, even go so far as to undergo hormone therapy or gender reassignment surgery, but they should decide on these life altering actions WHEN THEY'RE AN ADULT. Until then, dress as a girl if you please, but no one has to call you she or go out of their way to accommodate what could be the temporary whims of a small child.