Jolly,
I'm flattered! The second photo is my very own beloved DODGEZILLA! At anyrate, the trailer with Gary Radford's '59 Apache 3200 on it had a 20' deck, plus another 6'(as I recall) deck over the gooseneck. I forget what the GVW of the trailer was -- I think it was about 20k lbs, though. That trailer's normal job was hauling about 700 bales of hay twice a week from the Hillsboro, Ohio, area to Lexington, KY. (About 14 tons -- overloaded? Probably -- didn't seem to bother either one much. Besides, I had to make a living somehow after I got out of the Marine Corps). Neither Dodgezilla or the trailer had any problems with that. In fact, on the long hill coming south out of Maysville, KY, I routinely gave the other similarly loaded truck ('97 Chevy 1-ton w/6.2 diesel) a 1/2-mile head start and I still blew by them about halfway up -- that pig 6.2 was putting out more smoke than one of your trains! But I digress...
The trailer came from a manufacturer near Louisville and had ramps that slid into the back of the trailer under the deck. Deck over trailers like this are higher than that first trailer, but they sure are a lot more versatile. Just remember you'll have a higher center of gravity. I don't have a problem with wood-decked trailers. As long as you inspect them regularly they won't fail unexpectedly. Plus, if you need to, you can always nail or screw chocks or whatever into them if you need to. I've used some aluminum-decked trailers that "sing" to you at highway speeds (very annoying).
As for the hitch set up, I've had flipballs installed in both of my Dodgezillas (first in Hawaii in '96 and the other here last year) both times cost $800.00 out the door. Go with a flip ball rather than a fixed ball so you can still use the bed of the truck for carrying plywood, etc. Also get the recessed safety chain attach points for the same reason. The electric brake controller you can buy and install yourself for about $100 or so. Get a good controller (see the Links page). I assume your truck is already set up for trailering with an electrical plug? Hopefully, it's already a 7-wire connection. The lighter duty 4-wire won't allow you to use the electric brakes. I prefer the 7 flat "RV" style plug to the 7 round "horsetrailer" plug. The RV plug is bigger and easier to handle (I have big hands and a small brain). I can't tell you how many times I've yanked on the horse trailer plug and had it come apart inside. A real pain in the patootie to sit on the side of the New York Throughway trying to get brakes working again because that stupid plug worked apart.... (Good thing I didn't tell Gary about that...).
Does that answer your questions? The bottom line is that if there's anyway to swing it, go for the gooseneck, deck over trailer with 10K lb axles. You'll be much happier and you won't be trailer shopping again in a year when you get so sick of that tag along you can't stand it anymore (been there, done that, got the t-shirt AND the coffee mug).
Regards,
John