Do I need a return flight to Thailand when applying for a 6-Month METV?

Hi all, Im a UK resident and im about to start application process for a 6 month MEV - I have the first 60 days planned before I leave and go to another country for 3 weeks but after that - apart from a flight into Bangkok Im unsure of where I want to go and have nothing booked. I will add a departing flight within the nxt 60 days as required. My Q is - do I keep it simple with just the first 60 days and departing flight detail or do I need to add the return into Thailand flight even though I dont know where I am going then? Im aware they like to see accommodation details etc - which I dont have….. 🤷‍♂️🇹🇭. Thanks for reading