Anderson connectors: if too small, is that a bottleneck?

Anderson Power Pole connectors are available in different current sizes, to fit the appropriate gage wire. You should use the appropriate size for your projected maximum current. I use Anderson Power Poles all over for most of my 12VDC amateur radio connections. HOWEVER - I don't think they are quite physically robust to use for your described usage. Instead, I would use the connectors that Zamp solar uses.... which are nothing more than the standard two pin trailer plug readily available in hardware stores.