I have taken my car into Cambodia a few times and they do only LEGALLY allow 30 days out pf Thailand, 3 times i was over, ( once was 2 months out, once was 4 months , once was 9) each time they asked why i stayed out an just told them ( crossing back at Osmach, Poi Pet and Pailin) that i liked Cambodia, Once i told them the car broke down an had to wait on parts.
NO problem