If you are considering only two "outlets" able to be powered by the inverter, consider just wiring the inverter OUTPUT to two outlets.
What is amp draw to charge your eBikes?
What size battery bank do you have?
Wonder if generator run time to recharge the batteries will be any less than generator run time to charge the eBikes directly-- neither charging nor inverting process are 100% efficient, so you are loosing efficiency at both ends.