I will be offering skull whitening services starting this year. Bring me your cleaned and degreased skull, and I will put it in peroxide for you. This is industrial strength peroxide, expensive to purchase for whitening just one skull. But, it does a better job than simple white or low volume peroxides, by far.
Call the shop or cell for specifics. I expect it will cost about $35 for a black bear and $45 for a brown/grizzly.