I'd be willing to trade the metal rear fenders on my '37 for FG ones but that's only because I think my truck has '36 rear fenders on it... Lots of room to tuck any width of rear tire inside them as they aren't as teardrop shaped...
I'll be watching this one with interest to see what you come up with... I know I've seen wider glass rear fenders on ebay that a guy custom makes but they'll require you to empty your wallet and back account to get 'em!

~Trev