Training wheels, as you've probably noticed, there's a lot of very high terrain west of CNX and with cloud base usually greater than 5 Octas this time of year, flying VFR can be quite a challenge.
If you're flying IFR and wish to proceed direct CNX to RGN, then the LSALT is around 9000 ft for some of the leg. What type of aircraft do you intend to fly?
I haven't heard of anyone flying to RGN on a private flight, but you might want to check out the Thai Flying Club homepage at
http://www.thaiflyingclub.com for more info.
Good luck