One thing I forgot to mention about the THOOSA is that when you are under sail you can set it to recharge the battery (60ah max, with voltage limit). How much this will slow you down is an open question.
Reducing the size(Kw) of the generator gets pretty tricky. You can go more batteries and just run the generator longer(say a 5kw) but how much more weight (batteries) can one afford?
Having a couple of solar panels (100w?) I had just assumed was the standard now.