Why don't you settle for native amphibians?
You'll have perfect weather conditions for them and they might be even more interesting then non-natives. Even more, you could contribute to better understanding they behaviour by working out how to breed them possibly you could support local populations in case they would start disappearing.
When I was a kid I've done similar thing with T.vulgaris and T.alpestris back home in Poland. I was collecting adults from a ponds around, collecting they eggs and raising larvae. After the breading season the adults where going back to the pond where I collected them as I didn't have facilities to overwinter them properly. I was raising larvae and later morphs till early autumn and them some morphs where going back to the pond where the adults where from while other youngsters where going to new ponds. After around 20 years they are still in a places I introduced them!
Don't go for endangered species without getting enough experience on similar common species and without contacting local herpetologists first