Mumbai to Kerala Road Trip

I'm planning for a road trip from Mumbai to Kochi. Ideally planning to take Mumbai - Pune - Satara - Kolhapur - Belgavi - Hubli - Tumkuru - Hosur - Salem - Erode - Coimbatore - Thrissur - Kochi route. Roads are bit confusing after Salem as G Maps suggest many internal routes. Looking for suggestions from those who recently traveled from this route which highway to stick with after Salem?