This recent custom job (http://www.tfw2005.com/boards/radicons-customs/318770-jet-convoy.html) just gave me a radical idea/suggestion for anyone who wants to create their own custom ROTF Ultra Magnus: 1) Paint an HFTD Leader Battle Hooks Optimus Prime white like G1 Ultra Magnus or white and blue like Classics Ultra Magnus. 2) Paint one regular ROTF Leader Optimus Prime head white for his regular robot form, modify (and paint in red & blue) one HFTD Leader Battle Hooks Optimus Prime head for his super robot form, and make them removable/swappable for each form. 3) Modify an ROTF Leader Jetfire or two so that it is more movie-accurate and can ride on his vehicle mode like a trailer, then paint it in the blue/red/white color scheme as his tractor trailer/armor. Combine them altogether and you might have yourself an ROTF Leader class Ultra Magnus with removable armor, like is G1 predecessor. In fact, his Movieverse bio can go like this:
I would look at using something like a Voyager class prime, with a custom trailer that becomes armour. Make him more or less in scale with Leader prime and you're golden.