Used Color Oops - Help Please!!

Hi,
Has any body got some advice before I go any further.....

I had Copper Red hair until about 3 months ago. My hair has been every colour in the Red spectrum since mid 2010 when it was a level 9 Blonde. I've used a ridiculous number of tints and demi's to keep the red in, I never used a filler because I didn't want brown tones. Tired of constantly dying my hair I decided to use Color Oops and go back to my favourite shade of Light Beige Blonde.

The Oops performed quite well considering it is only meant to take out the last color application. It took my hair to a level 8 bright yellow gold. Toning it with a purple based toner was ineffective. I then used a tint Natural Blonde 8. It turned horrifically muddy. I did a test strand first, but the overall effect was much darker and I was desperate to be rid of the chicken yellow!

I wouldn't use bleach at this stage because of all the previous times it has been blonded and bleached. Admitting defeat, I mixed up a little demi tint with copper red and left it on for 10 mins. It turned my hair a nice Natural Auburn shade of about a level 7. I was content for a while until it gradually faded and returned to a Dark Muddy Reddish/Gold.

Frustrated, I used the Oopes again. It took my hair one level lighter and got rid of the red tones. Now it is a Medium Muddy Gold. Exactly the same color as powdered Turmeric! It's okay under artifical light, but under sunlight it turns a hideous Dark Gold with yellow/slightly greenish undertones URGH. I want my Blonde hair back!

My hair is Very Porous so I'm still hesitant to use bleach. My thought was to apply
L'Oreal Excellence Blondes Extreme Permanent
Creme Haircolor - B1, using a 40 or perhaps 30 Vol developer. It is a Hi-Lift Tint.

Does this sound like it might work???

Thanks,
Freya