I had started to but then sold the trailer and bought one in the floor plan I really wanted. You will probably need to move the tanks around. And you may run into problems with the rear being a lot heavier than OEM and could cause frame issues. But if you're tearing it down to the frame anyway, now is the time to beef it up so that you don't have problems on down the road.
If you need to move a window, that is some work, but it's really nothing more than cutting and riveting.
But anyway, probably the hardest thing about doing this swap will be the plumbing for it. If you can handle that, then it's not that big a deal.
I'd personally consider making a totally new frame and just reusing the shell. But it could be done with the original one too.
Best of luck. Should be a neat project,