I think anything that applies proportional braking will work, but I really like the electronic adjustment capability in the P3. It is very easy to make small adjustments as needed (and you might want to do that as the weight you pull changes), and, once set, you don't have to worry about the settings getting "bumped" accidentally.
With my old controller, I started out on a trip and discovered there was no trailer braking action. I thought I was going to have to cancel the trip but discovered the lever controlling braking force had been accidentally moved, possibly by a technician at the Ford dealership during a visit. I reset it, but didn't have an "exact" reset point - you have to do that by "trial and error" on a level stretch of road with someone observing the trailer wheels for lockup. With the P3, once you get it set right, you simply note the number that appears on the screen, and restore that value if it ever gets accidentally changed.
If your trailer can gross out at 7000#, your tongue weight will be between 700-1100#. You need a Weight Distributing hitch to keep the axle loads on your truck in limits. There's some pretty good information on WD hitches here:
Trailer Hitch & Towing Guide ? Hitch Info | Get Connected Basically though, you want a hitch that just about "matches" the tongue weight of the trailer - not rated too much higher, and certainly not less than the actual weight.
- Jack