That's what I was going to bring up. Hamsters in general, especially the dwarf varieties, have a very thick plush coat compared to rats and mice. Perhaps if you can't get mice or rats, are there any species of gerbils, that might be more available due to location? They are likely to be more meaty and less fur and bones. Other than that, there isn't much you can do but to feed robos. At least robos have tiny tiny teeth (and I've rarely been bit by them... when I do, they never seem to be able to break the skin).