A lot depends on PGs staff in RGN. In theory they should be able to check your bags through, provided you give them the details of your TG flight. Not sure if they will/can issue onward BPs? If you can check bags through, the following which describe int'l-int'l connections at SBIA/BKK.

http://suvarnabhumiairport.com/en/22...-boarding-pass

http://suvarnabhumiairport.com/en/96...-boarding-pass

If you cannot check bags through then you will have to clear arriving Immigration, retrieve checked bags, clear Customs, head from level 2 up to level 4, check in with TG, then clear security/departing Immigration.