For what it's worth. No platforms are technically legal. Unless the manufacture approves of the item it is not legal. Here in Ontario they are strictly frowned upon and face fines upto 5k if I'm not mistaken. From how I understand it the machine has to be operable from the work area.
Now that being said there are lots of places that make them and claim to be legal. I would ask for engineered paperwork either way if I was buying one.
Just my two cents
I know some guys who have a 16' platform that was welded and they've had it since 2004 and its going strong. They got the basic design from a buddy in the mid-west where a shop builds them and sells them.
I could probably get the original photos for you if you want.
The 'roof' on this was temporary but worked really well and allowed them to side for a few days w/out getting too wet.