I have read of Penguins in Germany pre war , but they had short wings so not enough lift to fly. Having full size wings but lacking power seems more dangerous. I dont think I ve ever flown a tailskid type, but just a tailwheell plane is not so hard. And you dont need to spend much time at 70 mph to learn tailwheel handling. Taxiing around a wide open ramp area at a fast taxi can teach a lot. Before I had a full type rating in my tailwheel plane, I used to taxi solo around APA airport a lot and got the feel of it. Just taxing on a narrow taxiway is too confining, I guess one could practice on a runway when not busy.