Based on 26 years experience in a liveaboard marina, and on working on the electrical systems of many boats from 30-130', here are a few observations which might be helpful for the OP:
1. A single 30A power cord is likely to be insufficient for your liveaboard requirements. This is because the 30A design is itself flawed and -- unless brand new and sporting tight, clean contacts -- it won't really support a continuous load of 30A without overheating/melting. I can't tell you how many we've seen with burned contacts, meltdowns, etc.
2. The usual way of getting more power aboard for many boats is to add a second 30A circuit. Sometimes, even a 3rd 30A circuit is added, as was the case on my 44' houseboat. The additional power is required for heaters, appliances, and even ice-eaters in winter, and A/C in summer. While three 30A circuits seem like a lot, remember that it's really not safe to load any one of them more than about 25A.
3. Many boats use "splitters" which can take a 120/240V circuit and "split" it into two 30A 120V circuits. These are serviceable but, IMHO, are potentially very dangerous because it's possible to attempt to draw as much as 50A through EACH 30A cord attached, as the CPD upstream on the dock is 50A. Again, this practice frequently spawns overheating and meltdowns.
3. A much more satisfactory way to get additional power aboard is to use a 50A 120/240 circuit. The inlet at the boat is the same size, and carries four AWG6 wires from the dock. This can provide up to 50A in each of two 120V circuits aboard, for a total of 100A. We have converted many boats from two 30A circuits to a single 50A system with great success and satisfaction from owners. A single thick shore cord makes a neat connection which is far more robust than the 30A alternative. The downside of this is that it's a bit expensive: 50A shore cords are quite expensive, but they are the standard among larger yachts. If you shop around, you can find some deep discounts, though, and these 50A cords will generally last a lot longer than the 30A cords for reasons cited above.
4. Re: generator sizing, remember that the power factor of attached loads is important: inverter/chargers, A/Cs, frigs, etc. can place very heavy loads on generators. There's another very informative thread on this subject here:
Gen / Xantrex Charging Problem
Hope this helps a bit.
Bill