DO NOT weld those together. You will regret it.
Look at any one piece wheel. The step on one side is (almost) always shorter than the other. The short side is the side you work from. It allows the bead of the tire to shift over and let you pry the bead over the lip on the opposite side. MOST 2 piece wheels have no step down. You have no idea the nightmare changing a tire with no step in the wheel. You will either kink the bead cable or skin it to the metal....ruining it either way.
I've noticed something around here. There seems to be an aversion to running a tube in ATC tires. I cannot for the life of me reason why. I have tubes in EVERYTHING but my Toyota FJ. Maybe it's the added cost or the trouble some people have putting them in, I do not know BUT, I NEVER have a tire leak around the rim. I suppose there's an argument for trail repairs but that doesn't concern me at all.
I have a 2 piece wheel on the front of my current build. I got the wheel from Ps2fixer and I cleaned it up, slapped a tube in that puppy and rolled with it. A gasket or O-ring might seal but a tube WILL ........unless you're a gumby and pinch it while putting it in. LOL!
I was born and raised on Venus & I may be here a while.....