Replacing a 55 amp converter with a 45?

I just realized something that might be significant to my decision. My new trailer has 12 volt heating pads on the holding tanks. I have 2 gray tanks, and of course a black tank. I have no practical experience with that aspect of the 12 volt side of life, but the spec sheets for those pads show an amperage draw of 9.9A for a small one. If there were three heating it would be a 30 amp draw. That could be a game changer as far as boondocking goes. A bigger battery bank and a bigger converter to charge the bigger battery bank might be prudent. Even hooked to shore power, a 30 amp draw for a 45 amp converter is not a good thing. The trailer also heats the tanks by blowing a portion of the furnace heat to the holding tank areas. The dealer indicated the best use for tank heaters are when you are going down the road, when the furnace should be off. Like I said, I have no experience with tank heaters or the philosophy of use of the tank heaters. I don't plan of using my trailer in weather that cold, but you never know what you may unexpectedly encounter.

Thoughts?