IMQ: What do you dress your DC in at night if they sleep in air-con?

What do you dress your DC in at night if they sleep in air-con and refused to sleep with a cover on? We've just recently moved to north Queensland from Brisbane where we had ducted air-con so have continued to use the air-con here for DS at night. He's 2. He sleeps in a bonds one-piece wondersuit and a bamboo fabric light sleeping bag. We're going to have to give the sleeping bag up sooner rather than later as he's growing like a weed. He won't sleep with any sort of a cover on and gets distressed even when sleeping if I try to cover him. I'm worried he'll get cold in the wee hours once he's not sleeping in the bag and sleeping without a cover on. What do I do? The place we rent has box-rattler window air-cons so pretty much non-adjustable for turning to sleep mode like we used to - and it's really difficult to determine the degrees as I have a choice of turning the dial from 1 - 11, with eleven being freezing. They also are 'click on/click off' air-cons that 'click off' after a short period and the room starts to get warmish before the 'click on' again. The thermometer gauge we have in his room runs around 23 degrees when it clicks in and goes up to 25-26 degrees when it 'clicks out'. We also have a fan on in his room. What is the best way to manage the room temperature for him once the sleeping bag come off, or what is the best clothing to have him in to cope with the fluctuations of temperatures all night?