Bleached Blonde to BLACK...temporary?

Hello all!

I am currently a light golden blonde (level 9 if you know levels), naturally a dirty ash blonde (level 7). I lighten my long, fine hair with hi-lift blonde and have damage control down to a pretty workable situation. (been doing this awhile)

I am considering making a drastic change to black. I know this would be a 2-step process that would involve depositing red, then later black into my hair. I'd like to use a temporary (ammonia-free) color to try this look out BUT I am hesitant to do so if I can't go running back to my almost-platinum locks if the black is too much and it turns out blondes really do have more fun :)

I am assuming that, even without ammonia, my hair is SO light and SO porous that it will soak up these reds and browns permanently and put me in a situation where i need bleach to get them out. Anyone know anything about this?

Thanks in advance for your insight!

Brittany