You should install a plug on the wires coming from the receiver or switch. You don't want to solder the battery wires to the receiver wires or you can't remove it without cutting and ruining your connections. With the plug, you can just unplug it, which comes in handy when you are running a lot and keep a spare battery charged and swap them if the first one goes dead.
Oh I almost forgot, you could just buy a new switch from the LHS for like 2 bucks, and it will have the plugs that you need. You can install that switch in about 2 minutes and be good to go with no soldering, and you will have a charge input on the switch so you can charge it while it's still in the truck, which doesn't sound like a lot at first but it comes in handy after you've taken it out a few times just to charge it. I would HIGHLY reccomend this method over soldering unless I'm wrong about this, wait and see what some of the veterans say.