You could probably get away with an 18ft car hauler with 3500lb axles. BUT, i would suggest 5200lb or 6000lb axles. When I was looking a few years ago, the price seemed to jump when you went to the 7k, but the one posted above seems to be reasonably priced.
I like to lean towards the 'overkill' side so that you don't put as much stress on the equipment. Bigger axles should have larger bearings that will not wear as fast, but they may cost more to replace. You can go too overkill though, and that is what I am running into w/ my GN. It is great for texas trips, but it is a heavy mother in places like Co where you are pulling some good hills. I use it at the ranch though, so I need that extra strength. It gets called into Bus hauling duty now and again too, so you never know when you need that little bit extra.
Brakes on one axle works fine for me pulling the heavy Bronco with a half ton, but some will insist on both axles. I have heard rumor that brakes on both has caused inconsistent tire wear, but that could be a myth.
I have never heard of the 2 brake/tire wear, but that doesn't mean it's not true. Again, 'overkill'. With the stop and go traffic in Dallas/Houston, you want all the 'whoa nelly' you can get!
Make sure whatever you buy has new trailer tires, and not retreads.
Here is where I disagree somewhat (or just want to elaborate more I guess). If it doesn't have new tires, or has retreads, just make sure that you account for that in your purchase price. Good true trailer tires are hard to beat and pay for them selves pretty quick when you don't have blow outs on I-35 w/ traffic roaring past you and a ruined rim under the trailer. To me, this is very important especially when I haul other peoples vehicles, as I feel responsible for them while they are back there...
Steel deck v. wood deck is a toss up. You could hear arguments for both, but a treated wood deck is going to be a little lighter.
2x12 treated lumber is roughly 6.6 pounds per square foot. 1/8" plate (0.120") is 5.1 lbs. You don't save any weight until you jump to 3/16's, but I don't know how well 1/8th will hold up.
At 80inches wide, you are not going to need to worry about drive over fenders. My trailer is 83" between the fenders and I sqeeze all 86" of Bronco through them.
I would look for a 20' trailer, treated wood deck, dovetail, 2 6lug axles with brakes on one, 2 5/16th bulldog, good beefy tiedowns, LEDS, and new tires with a spare.