How did they get at him, did they knock the lid off?
I have bred crested geckos for a few years, and have had a few lose tails, it's no big deal, the geckos get by just fine without it and if anything seem to move even faster. Lol
The only thing that would worry me would be internal injuries, but it sounds like your vet options are limited, and most wouldn't have the know how to repair such injuries surgically. Best option is to keep him well hydrated, at optimum temps, and hope all goes well.