The usual thing with multiple devices is to add up their input power ratings, so long as they add up to less than the inverter capacity you should be fine. However based on safety keep the 240V section close to the inverter, IE no long runs of extension cord. The inverter should be fed in a direct way from your main battery, a manually operated circuit breaker of around 70 amps should suffice to isolate it:
Marine Auto RV's 12V 70A Circuit Breaker Manual switch reset Surface Mount | eBay

