I pull a 24' pontoon boat with a dual axle pontoon trailer with 10" wheels. About 5k lbs total loaded. It is about 20 miles each way from the boat ramp to the house. 2WD EX V8 Limited.
Backup camera is AWESOME. I can now hook up the boat by myself in less than 5 minutes. Gas mileage is worse, but not enough distance to know just how bad it actually is.
Borrego pulls the boat out of the water without any strain. The Borrego actually pulls better than the 1990 Suburban automatic w/4x4 I was pulling with before. The Sub had a v8 (rebuilt), but just had a lot of trouble with the boat on going up hills. The Borrego 6 speed trans has been great pulling the weight. I have let it auto shift on its on, and I have manually shifted it, just to compare how well it does without me touching it. I was a little more happy when I manually shifted it, but it still did well in auto. Nice to know that it can do it all on its own if needed though. The Sub did not do well on its own, and had to be manually shifted all the time and was a pain in the butt.
I also converted my boat trailer over to disc brakes. It helped a lot! The disc brake kits for the 10" pontoon boat wheels work great! Only took a weekend to install them.
Where I go to launch, they keep the boat ramps very well maintained, so a 2wd is fine for pulling out of the water. I've had the two back wheels wet (axle not submerged), and have had no issues with slippage when pulling out. I never had to use the 4x4 with the Sub in 5 years of going to that boat ramp.
I also have an electric brake controller for some other trailers. I have the Hayes G2. It is hands down the best controller I have EVER used. Check it out if you are looking for an electric brake controller.
Hope this helps...