+1 to Rich & Cindy. We have a factory (OEM) controller in our truck, and it is proportional by design, and it fits into a slot specifically meant for it. It also ties in with our console to indicate that it working & even how much pressure it's applying to the trailer brakes. I installed it myself, because it just plugs into the plug behind the dash. Easy peasy. Our truck did require it to be "activated" through the truck's computer system, but that was easy too with a tool (for Ford vehicles) called Forscan.
I do have to ask how much your Coleman pop-up weighs? In most states, you don't need a trailer brake controller if your trailer is less than 3000 lbs (that number does vary state-by state,, but it's a good rule of thumb). Also a half-ton pickup "should" handle trailers up to around 5,000 lbs without a WDH. Notn saying you shouldn't use one (we do), but it's not a make or break kind of deal.