Gooseneck progress

I seperated my boxed mainframes and leveled at 58" center. (7k axles with 58"
spring centers)
I looked at 10k axles, oil bath Dexters, and at $1150. ea. I figured I'd go with 7k
$400. axles to start...($750 for 3k more X 2= $1500 for 6k more)
Of course I would prefer tandem duals, who wouldn't? (trying to be reasonable)
Brakes on both axles.
I figure if I change my mind I can make special brackets later for different spring
centers. (have learned from axle manufacturers that if you move or change spring centers on axles in ANY way the ratings change for capacities)
I'm just including all my thinking here for whoever may be interested...
I cut and welded 6" channel crossmembers (4 total) at 57 lbs each.
Mainframes are 520 lbs ea, X 2 = 1040 lbs
Mainframes with crossmembers are 1268 lbs

Set up conveyor for horizontal bandsaw.

First two crossmembers.

Bought I-Beam, 576 lbs @ 18 lbs per foot.

cut uprights.

Welded two uprights and inside crossmembers.

(I cut 19 degree angles on top of uprights which is a matching angle to the

forwards connecting GN coupler, strictly aesthetic)

Beginning Deckover Gooseneck

I've decided that the absolute best all around trailer for hauling anything from cars/trucks to equipment such as large horizontal bandsaws, forklifts, tractors, shipping containers or just steel from foundry is a Gooseneck deckover. It's obvious that when the trailer is connected directly above the pulling vehicles drive axle, it will be inherently more stable, as well as, easier on the towing vehicle, safer and easier to control.
Thus, I've determined after looking around at other trailers and PRICES that I need to build my own. I don't have any plans, I searched for some and it couldn't financially make sense. I looked at quite a few trailers and I've chosen to build my own from what I've seen and what makes sense to me. I bought some steel channel, both 4 inch (6.5 lbs per foot) and some 6 inch (13 lbs per foot) both in 20 foot lengths. I looked at some of the I-beam used in these commercial trailers and frankly it sounds tough when they write about it, but if you go look, it's actually some thin stock (low weights per foot) so I decided to take 6" channel and face two together and weld, that way it's completely boxed, has two vertical sections etc. Yes, it's 26 lbs per foot, but very strong! For those of you that realize it, yes I am overbuilding it for my own piece of mind.
I have mixed feelings about welding the mainframe channel solid, on one hand, if I leave them stitched (as I call it) water can never be trapped inside and isn't it really sufficient as it is? On the other hand, wouldn't it look good welded solid and ground down to look as though it's made that way? Though I believe it would be stronger welded solid (at a greater cost) I don't believe it's necessary.