So in the end I did buy a 2009 KLX250 with 41000km on the odometer in CM, and did some 15000km traveling all over Thailand since then. Bike is giving me no problems whatsoever! I live in Prachuap Khiri Khan now, doing some traveling from here, but next week I will come to CM again, for a couple of weeks, plan to do some traveling in the North!
This thread can be officially closed
Some mods I've done:
Added thicker gauge (12,14,16 AWG) wiring for the main headlight, aux LED lights, aux power socket, GPS power. Powered the main headlight using the new wiring harness and sealed Matsushita relays. Added crazy bright aux LED lights from ADV Monster (4 CREE XM-L LEDs in each light), powered using the new wiring harness and another relay, which also powers an aux power socket with a separate fuseholder. The aux power socket goes into my tankbag, I have a 2A 2xUSB port charger with a matching sealed connector, use it to charge my phone, music player, Bluetooth headset, 18650 charger inside the tankbag. Also if my GPS dies, can put my phone in the tankbag's map compartment and use the phone's navigation, while powered from the USB charger.
Used sealed fuseholders and connectors everywhere (also replaced the stock headlight's connector with a sealed one). Added two push-button switches to toggle the aux LED lights and the main headlight's LO beam.
Also, I replaced the stock left handlebar switch with one from a Kawasaki Versys 650, which gave me a Hazard lights button and a Pass button.