Enigma like cipher machines are still secure for Shortwave messaging ... using RTTY not Morse circuits.

Mind you most would view that these modifications would be needed :

1. Rotors would need to have an alphabet of size 36 and at least 4 rotors yielding 36^4 raw keys.

2. One would want to have at least 8 different rotors.

3. There would need to be a plugboard of at least 12/36 in size to force hill climbing.

4. At least 1 rotor would need to have irregular stepping.

That said, encoding a message with AES and then recoding it for Base-26 and then whitening the data with an Enigma without a plugboard would be far better.

Or just increase your cipher strength on your computer.

In the intervening time my views of the utility of the plugboard have changed.

The plugboard and the reflector are simply don't add that much extra security, and in the case of the reflector -- decrease it.

For base26
-- a 3 rotor 'data whitener' is needed aka commercial enigma
-- you would need to have 5 rotors
-- you would need to have to choose between at least 25 rotors overall but ~100 is better

For base36
-- 4 rotor 'data whitener' is needed
-- you need 6 usable rotors
-- you would need to choose between ~100 rotors