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.