I also looked into widening cookies, I found a company that can, but when I inquired about it locally I was told it might be risky - for the same reason - that it's cast aluminum.
Alternatively, I reached out to AWC, the company that did the custom AMMO car wheels and they said they could do a custom cookie-esq wheel. It looks to be about a 4k proposition though.
I thought it would be cool to do a special offset (like a 911R, but 31mm offset instead - so no spacer needed for a n/b car) cookie, with a bit of a modern twist. It would be deep dish, and allow a 225/50 sized tire in the rear.
The above photo, is one of two cars that I've seen with widened cookies. Here is the other.
