Here's a link to a video showing 7-pin to 4-pin... opposite of what you're doing, but same principle and connections. It's likely there is no wiring for a brake controller if you have a 4-pin. But if you're installing a brake controller anyway, stringing the wiring from the rear to front is fairly simple... probably the easiest part of the whole job.
https://youtu.be/hqze3Qgz-Ng
If you're going to tow anything - trailer OR flat tow - I'd go ahead and at least install the 7-pin connector and run all the wiring required from the connector to the steering column area of your motorhome... basically a "brake controller prep" which is how nearly all newer Ford chassis are prepped.
Then when the time comes, installing a brake controller for a trailer OR using a signal wire for a flat tow setup, the wiring is already there which makes it simple.
Some brake setups require a "signal wire" from the tow connector to the motorhome cabin (dash area) which gives a positive indication (tone and light) when the aux brake is engaged. In addition, although not required, an auxiliary 12 volt charge line from the connector to the toad battery is suggested... just eliminates issues down the road. If you convert to a 7-pin, all this wiring is included in your prep procedure.