I did India, Nepal and overland to Europe on a CX500 two up with a trailer. One thing to consider when travelling in third-world countries is that you will be travelling on third world roads. That means potholes. Lots of them.
BMW used to make a car named Isetta. It had two wheels spaced apart normally in the front and two rear wheels very close together in the back, which did the steering. That way they saved the diff. The Germans quickly nicknamed this car the Pot Hole Detector!
That's what you will have towing a normal trailer. I've seen holes big enough if you'd chucked us, our bike and the trailer in them it would have been about level with the road. I've also seen a few trucks that went too fast through those holes. The front axle came right off.
In India I can recommend therefor only one-wheel trailers, and that's what we had. They used to be very popular for a while in Holland, apparently named Freebird. (Don't know whether this is a brand name.) There are still companies in Holland and France making them.
I built one myself: went to the wreckers and bought the frame with rear end of a 100 cc farm bike. Chopped the steering head and the upper frame tube off, bent the whole lower part of the frame flat and built a tapered steel box with lid into it. Nice and solid and lockable with padlock. For a coupling I used the universal joint off a power take-off shaft and a matching splined shaft, which I got for next to nothing from an ag machine shop. Fully loaded this weighed probably 50 - 80 kg.
Two up handling was a bit funny, but quite manageable. We even negotiated a couple of pretty bad and steep dirt roads, but that wasn't fun. In Iran I rode alone at 140 km/h through long bends without major wobbles. Don't try that on an airhead BMW, though. I've got a picture, but nowhere to post it.
I don't know what other Asian countries are like, but I think if you try towing a 2-wheel trailer there you'll loose it.
Salut from Southern France, the bikers' paradise,
Jenny & Peter.