You should keep flying this electric plane. Although the "fuel" trainer will have a little more power, it will all in all fly the same as your electric. Keep flying the electric Superstar EP and then move on to a Sig Somethin' Extra or something. That is an incredible second plane after the trainer. Since most second planes are taildraggers, you will already have experience because of the Superstar.

But if you insist, then I think yoiu could just move to the Superstar ARF or RTF. It will cost more than the EP version, but it is a tricycle gear configuration, and is a great "fuel" trainer. I've been flying for 5 years, and still have my Superstar RTF. I believe the RTF (includes engine(OS 40LA, radio(Futaba Skysport 4 channel, and servos(Futaba 3004s standard type which is ALL already installed and literally takes 30 min to put together (join wings, assemble tail section, and atach landing gear, then charge batteries of course!!)

Hope this helps!!

~Michael~