If you do not want a battery forward draw from the house bank for the windlass. Larger bank so much less of an issue. The engine start battery ideally is only used for engine, fuel pump if there is one and the panel. If your system is designed like most recommend your charging sources go to the house bank and either an Echocharge or ACR charges the start battery. 4/0 is fine but not inexpensive and will give you a 2% drop. Make sure to fuse it near the battery. And make sure the ends are properly crimped and covered with heat shrink for waterproofing.
Living aboard in Victoria Harbour