OK WKC, here's one way to do it. Apologies for the crude mockup, but I prefer rapid prototyping to a more time consuming "pretty" mockup. If it works out I can take my time and do it right. I don't plan to use this anyway, and I only had an hour to spare today. FYI - a Gennie frame is too narrow to mount an 18.5 WSM, but a little hacking and you'll have a very useful smoker cart.
Take your standard Genesis frame. (This one I've used before, and has been a mule for other mockups.)
Unbolt the top frame and flip the right side end for end.
Cut off the (now) outboard ends to use as center supports. You should have about 18" or so. You'll also cut the inboard ends to match the other side, and cut the protruding tabs off the ends on the left.
See the overlaps? That's where you would drill and bolt the sections together. Drill a couple more holes for the brackets, and the WSM with drops right in!
Fab a couple wood tables (don't use pink foam like I did) and you're done!
All in all, pretty simple job: A few hack saw cuts, and a few drilled holes. You would probably want to get some more 1" end caps for the raw edges. The height is about 2" taller than the Platinum cart version - putting the top grate height at 47". Now, let's see someone do this right!