Drive BKK to Koh Chang

Hello! Me and my partner need to get from Bangkok to Koh Chang in a couple of weeks. We have been quoted around 3.8k THB each way for a private transfer. Of course the bus is much less than that but we don't have the time to waste half a day each way travelling.

I have just searched and I can hire a car for roughly 1.1k per day, which even with fuel costs is less than the private transfer.

My question is - is this a sensible thing to be attempting?

I am a confident driver, although I haven't driven a car in SE Asia, only a moped in Vietnam, but felt confident doing this. Is it a reasonable drive to attempt to manage myself?

Is there anything I should look out for, car hire companies to avoid?

Hidden fees, scams that's kind of thing?

Any help would be greatly appreciated!!