I bought a 8 ton GN trailer with true 12" I beams for the frame with brakes on both axles and 25' length. The trailer itself weighs around 5600 pounds empty, so that leaves me with roughly 10k trailering capacity. I know you said that you didn't want a deck over, but compared to the bumper pull type of trailer pulls, there is no comparison on how it handles the load. Major league difference. I had to try one first to see how much of a difference it makes in the ability of your tow vehicle to handle the load. It's like the difference between you pulling with a 4 cyl S10 pickup vs your current truck.
The best part is that the brand new 2005 model complete with a spare tire, break away brakes and all cost me $3600! /forums/images/graemlins/cool.gif When I park this beast next to the puny looking trailers that I've seen for sale for nearly that cost that weigh 2500 pounds, I think I got a tremendous more amount of trailer for my money. Besides the frame being all 12" I beam, all the other steel on the trailer is 6" channel.
It may be overkill for what you need, but it sure makes hauling my 7000 pound Kubota L5030HSTC (with loader and 6' bush hog) much less than an adventure. Here is a picture of my tractor on this trailer. In the pic, I only have a little PHD on the back. Either way, you get an idea of what you can get for $3600.