Ford Explorer Towing (was prospective owner)

The Trail-Lite's dry weight is 2087. The Trailmanor 3124KS dry weight is 3185. When we originally purchased our Trail-Lite, we were pulling with a '99 Ford Windstar. The rating on that were 2000lbs; with a Class III hitch, we could go to 3500lb. Our van averaged 24 hwy without the trailer and about 14 with the trailer. I'm in Central Pa and mostly travel in and around PA, MD, NJ, VA for various dog shows. We never had any problems pulling the trailer; the van never overheated or anything, I just thought we'd be safer with something a little more heavier. So now I've got a 2002 Ford Explorer 4.0L, 4-dr. 6 cylinder, 4-speed automatic transmission, factory Class II hitch, with the 3.55 gear ratio. We added a Class III W/D hitch w/anti-sway bar that is mounted underneath the factory job. I'm confused about what I can pull and what I can't. In the book it is rated for 3500lbs. and then it goes on to say that if you are using a class III weight distributing hitch you could go to 5000lbs. In some of the on-line tow rating guides, I also see 5000-5500lbs mentioned. We did climb some steep mountains this past week with the Explorer. Had no problems. Pulling the trail-lite with the Explorer, I'm getting about 11-12 mpg.

There's not a lot of weight difference between the 3023 and and 3124KS (about 200 lbs). And since I'm travelling with two performance dogs, I need room for two crates. It looks like I could put them right between the counter and the table and move the chair to the other wall. What do you think?