Much useful information here. Regarding Factory-Installed or Retro-Fit, my choice would be factory-installed almost any day. When I discovered that I could have my local Ford dealer install a Ford Brake Controller seamlessly into my dash and tie it into my in-dash display, the knee-mounted after-market option was abandoned hurriedly.
Regarding WiFi, and I will soon be very dependent upon RV WiFi - as the sign said, "My internet went down the other day, I had to talk to the family. They seem like nice people." - I'd like to add my two cents' worth.
The $170 JEFA Tech: Long Range WiFi Repeater Kit for RVs
suggested by elind appears a great option and works well. What I would do, though, as the picture in their web site shows the kit to be nothing more than a Hi-Gain antenna and a Wireless N Range Extender, is shop on Amazon.com.
This is the RV "router"... actually a Wireless N Range Extender and Access Point that will take the Park's wireless signal and boost it, creating a (secured) wireless network of its own...
Amazon.com: Edimax EW-7228APn 150Mbps 11n Wireless Range Extender/Access Point with 5 Port Switch: Computers & Accessories
The antenna which, if you scroll down to the comments section, one reviewer claims excellent results in an RV, additionally saying, "Very easy to mount to an exisiting RV TV swivel antenna."....
Amazon.com: Alfa Hi-Gain Omni-Directional Outdoor 15dBi Antenna - 2.4/2.5GHz 4.8-Feet long Weatherproof antenna With N Female Connector: Electronics
You'll need this cable to connect the two...
The Amazon system is $25 plus $50 plus $15 plus shipping = about half price. But if I had the choice to go factory installed, I'm sure I would.