Frequency control is probably the biggest issue with homebrew. Commercial generators have frequency governors that keep the engine at the same speed regardless of the load (within the machine’s physical limits). If you don’t mind wandering between, say, 40 and 80 Hz, then you have more leeway. (You still need something to govern the voltage, though.)
At this very early stage, am thinking basic motor-alternator-inverter-battery on a wheeled dolly .. won't have $ to burn screwing things up, so will surely do lots more reading/listening before tackling it.
Appreciate your info !