How to go late game with Cobar-Bomb-Mortar?

I lose pretty much every game I play if my opponent can defend around 20 bloon adjustments. I go for a mix of moab maulers, artillery batteries for stall and misdirection for BFBs and can get decent eco, but I usually end up dying to ZOMGs. Is there a good strategy for late game with these towers, or am I basically just cooked if I don't kill them earlier?