I wonder how much inefficiency there is due to the inverter and the computer's wall transformer. Would it be better to run DC from the generator to power a dc-dc converter (which might have its own losses)?
Yes, it's definitely better to power everything using DC if possible. The best, reasonably-priced inverter I've found still draws 2 W whether it's powering anything or not. But it's difficult to get the right voltage and connector for every electronic device you might want to power.
