I did the homework on this for a long time, here is what I did on my Bavaria 49.
let me first say that the genny is a luxury to have and not a necessity, I needed it cause I was a live aboard in the UAE where I had to run 3X16,000btu air con units. if you don't intend on running such heavy 220v systems then I don't think it is worth the effort and money, you'll do much better with wind and solar.
I wouldn't go for the 3000rpm generators even though the idea is very encouraging considering the size, these generators run very hard and are more complicated with inverters and what not, basically they are pushed to their limits technically in order to be that compact. I had some experience with them before and I did not think they were very reliable. plus they can be loud. Therefore I prefer the 1500rpm gennys which I have used for a while with no issues, even when run hard with the heat we have here including the water temperature. the main issue with the 1500rpm is the size and especially when you want to install it with the sound shield.
I probably went overboard with this project but it worked out great for me. my boat has three heads, I stripped out the port aft head, sound shielded the space, constructed a small strong base for the genny and installed it there, it was also the perfect level relative to the water level for the genny. I also use the area as a small workshop and a store for all the tools and spares I have on board.
it was a great project and Im very happy with it, but to be honest if I don't run these heavy loads I rarely need the generator. I run everything from 6Xtrojan 105s (675ah bank) connected to 560W solar and an air breeze, for small 220v loads I have an inverter which does the work. Now that the boat is in Europe I rarely ever use the generator.
