Nah, perhaps some other time. Honestly, you'd be better off assaulting Peninsular Malaysia via sea invasion (North East-South West axis), simultaneously with some ground troops maneuver from your Thai controlled territory (North West-South East axis). The highways communication system over there is more than enough to ensure a swift campaign if a proper shock and awe campaign is properly launched. As for East Malaysia, there's not much troops disposition over there if your objective is the capital. But be warned, Borneon (Sabah and Sarawak) would still continue to fight even if the Peninsular fall.
Well, I suppose, you'll face full scale rebellion once you did control that country. Eventhough with a population of 30 million that's more than enough to become a pain in the butt.
MOTHER. FUCKER. 
