I'm arriving in to Kuala Lumpur from Singapore in a few days and have yet to sort out a travel itinerary for my time in Malaysia. I'm reluctant to book a flight from the capital to Thailand (my rough plan) at the moment as I'm unsure of how long I'm going to spend there/where I'll be going/what I'll be doing/what mode of transportation I want to take etc. Ideally I'd just like to sort this out once I'm there but most airlines won't let you check in unless you have proof of departure, so the onward travel requirement puts a spanner in the works for that.
Would a flight from Bangkok (or any other country, for that matter) out of the region be sufficient when I've made no actual plans to enter Thailand and leave Malaysia as yet? If not, is there a course of action I can take that doesn't restrict my flexibility too badly whilst satisfying the entry requirements? Thanks.
Edit: I'm a British national so can visit Malaysia, Singapore and Thailand visa free.