The best method I have found has been accomplished over 20 rifle refinishes later.
Since you have sanded it already at this point I would not waste your time with the oven trick. Go buy yourself a cheap heat gun and on a low setting keep the heat gun about 3 inches from the stock while moving it around. As the cosmo melts out to the surface wipe it off with paper towels. When it stops melting to the surface then you have got all the cosmo out you ever will. This method makes the oven trick obsolete.
Next step would be to use lacquer or paint thinner. At this point since you want as much light color you can obtain I would go ahead and use lacquer thinner since it will strip a little left over stain and also remove any grease left behind by the cosmo.
At this step you are not going to get any more dark color out of the stock, whatever color it is will be the base color you start with. So I would lightly rub the stock down with 0000 steal wool to smooth the finish out. Blow the stock off to get dust off or use a tack rag. Then really you need to choose what stain your going to use etc. and apply it. After applying the stain you will need to let it dry for 12 hours or so before using 0000 steal wool again to smooth the finish out.
After you have obtained the color you are looking for you will need to seal the wood back up after you stripped it of all moisture and sealant properties. You will need to choose between Boiled linseed oil if you want a warm but natural wood look, Tung Oil if you want to keep coating it until it gets shiny or use steal wool to dull the finish back down once the wood has taken so many coats of it, or you can use a Poly to give it a really shiny look that is durable.
I find that it is way easier to use Tung Oil or BLO in case you get a blem or scratch in your finish it will be easy to touch up and fix, with poly that is not easily the case. Remember whatever you do get all the cosmo out first or when you stain and seal the wood it will have a waxy feel to the touch and you will have to start your whole process of stripping all over again.