I am going to pick up a 82"x82" L.A. utopia spa this weekend, is it structurally ok to put the tub on its side while I back up the trailer to load it?

I've never had any troubles laying spas on their sides. The biggest things I would ensure before doing that is make sure all heavy stuff (motors, etc) are secured before doing this, so you don't take the risk of snapping any plumbing. A lot of spas have rather thin side material so you might also want to make sure there isn't anything that can put undue stress in a small location (like a log or rock). I've actually had to drag a spa out of a fenced yard on it's side. Still worked great when reconnected.