Use any alt that you can fit on, most jap cars run internally cooled alts so would be a good look.
The voltage ideally needs to be nearer to 13.4/13.8 once running with no lights.
A few oddball french cars have single phase alternators, these are super lightweight, less than 1/2 the weight of the cossie one, much much smaller, but only around 30amps, which is more than enough for your use.
tabetha