If you have another wireless router, you don't even need the standalone switch. All you need to do is give the second router a unique static IP in the same network as the primary router (so let’s say the primary is 192.168.1.1, maybe make the second router 192.168.1.2), disable its DHCP server, and connect them LAN to LAN (do NOT use the second router’s WAN port!).
Netgear has a pretty good illustration of this setup. It references their own gear, but the principles apply to ALL routers.
http://kb.netgear.com/app/answers/detail/a_id/965
The primary router in their example happens to be wire-only, but that only means you need to use different channels to avoid interference.
NOTE: You can, if you want to, put the switch between the routers, doesn’t affect the setup one iota. At 50 ft., not using a switch shouldn’t be a problem in terms of Ethernet’s reach (100m max before needing a repeater). But if you feel it helps, it’s certainly not going to hurt. It would probably be more useful behind one of those two routers to expand the # of available ports.