"You may have done all that you can do.
The only other option I see is to find a vet willing to fix it pro bono. You'd need to find an experienced tortoise vet. It just seems like the local news loves stories of "Shelly the turtle got a new shell prosthetic, and it's 3D printed!" Maybe they could get some good press. Who knows.
Then there's the challenge of actually getting the tortoise since it's behind a fence on someone's land. This might be the toughest part. Based on the brochure from the state that says you can take an injured animal directly to a vet, it seems like you'd be within the law to do so.
You could also make the argument that if you leave this injured tortoise in place, there's a chance that it could reproduce before succumbing to the injury, whereas if it were taken to a vet and rehab center, it may never reproduce again to propagate more gopher tortoises in FL. It seems like getting it vet care would be the way to go though.
Thank you so much for caring about this poor animal! That shell really is in bad shape.
The only thing I can say is that you can try contacting The Conservancy or CROW clinic. Gopher tortoises are a protected species. Either of these organizations may be able to guide you as to either getting the tortoise some help from an organization closer to you, or they may be able to send someone to get the tortoise (We are all located on the west coast of Florida. I'm really not sure, but I do know that we are not able to help with this as we cannot take a protected species from its natural environment. Either of the other agencies should be able to guide you. The Conservancy should be able to give you some helpful information as to next steps. CROW has a clinic and they may be able to help with rehab of the animal if the Conservancy can't help."
I already contacted CROW