Thanks VernDiesel,
I have (had) the factory brake controller, and the boat brakes were surge. The only "non-flats" towing I did was in western Arkansas. There are hills and steep roads, but the total climb amounts are much less than out west (hopefully that made sense).
I also welded additional I-beams along the trailer frame. It was an ultra-light, and I didn't think the frame would handle the additional stress. The boat was 3300 lbs with a ~500 lb. tongue weight. I also installed an airbag suspension system on the rear axle. It was the automatic kind with a pump controlled from inside (not a helper system). I did this because the tongue/pin weights caused the headlights to point too high at night. Even though they were 5000lbs each, I didn't use the airbags to overload, just to level the durned truck. I also welded* a 5000lb winch underneath the frame of the fifth wheel hitch. It had a remote control and I used it to pull the boat onto the trailer on steep ramps. I'll try to find a pic later and post it.
Happy new year, BTW.
Disclaimer: I traded this truck two weeks ago for a 2500 CC LB Diesel, that's why it doesn't match what's in my member info. I got a bigger boat that's around 12,500 on the trailer and need to be able to tow it.
*Got a friend who's a "real" welder to help. I'm kind of an amateur.