Home built toy hauler

I think a project of a toy hauler on a 40ft gooseneck hotshot trailer would be interesting, tandem 12K axles with disc brakes and air ride. You could insulate for full time living plus do your own layout! Would have to hold up better than a purchased junk quality one would...any thoughts??

The horse people have been WAY AHEAD of you already! They are called LQ's.
http://www.sundownertrailer.com/tlr-LivingQuarter.html
There are so many out there for sale now that don't need any work and twice as many for sale that do need some work.
So WHY would you want to start from the ground up on one when you can buy one for waaaay less than what you will end up putting into a project? :B

You mentioned goose neck.
Do a search of used LQ horse trailers. There's a plethora of those for sale. RV up front toy hauler in the back all set for you to go or buy one that needs some work. At least all the guts will already be there.

Here's a couple from a quick search in IN.

$5,000 pendleton, IN
http://indianapolis.craigslist.org/grd/5639956025.html

$10,000, IN
http://muncie.craigslist.org/tro/5656143385.html

7,500
http://terrehaute.craigslist.org/tro/5647536274.html

$100,000 :W
http://indianapolis.craigslist.org/tro/5655999716.html