At 46 sized electric there are a lot of ESC that have adequate BEC in them to do the job.. but I do hear you about having a bit of separation.. Usually at about 60 size or if I have a lot of money in it i will go seperate bec.. I solder the BEC input power leads on/in the main power connector for the ESC.. so when you plug in the battery you have power to the BEC. I zip tie the wires and or heat shrink them together so you cant accidently break a wire off. On the ESC you want to remove the center wire from the plug to the receiver-- i usually pull it out using an exacto knife to lift the tab.. tape it up so you cant make a short with it.. You dont want the esc and the bec both putting power to the receiver.. they will fight and it will end up in smoke...