They can make anything but the back log is several months. You'd be waiting awhile for a custom design from NineLives. I'm in queue for a custom splitter but he's just taking my design and digitizing it so we can cut splitters for my car as needed. It is
extremely expensive. I'm only doing it for convenience. I've cut four myself and it's easy but time consuming.
I don't use splitter rods even with a 5" splitter. Splitter rods can be a pain in the ass (when mounted correctly) and I wanted to avoid them. My chassis mount/air dam combo has 19 points of attachment and doesn't flex. I can shim the attack angle with washers. When we were building my kit, I picked up a set of rods from
https://professionalawesome.com/ just in case but I haven't needed them with the 1/2" birch plywood splitters. Alumalite would benefit from rods though because it porpoises somewhere over 100mph. Professional Awesome can build custom aero too if they are closer to you. I use NineLives because they are here in ATL. All that said, if I go off track I'll probably break my bumper due to the rigidity of my kit. Some drivers prefer the vertical flex of carbon laminated splitters and flexible rods. I just try not to hit shit. Time will tell..
If someone made a chassis mount it would be worth my investment in developing the best class-appropriate splitter design with NineLives that would likely cost around $300-$400. The chassis mount is more complex because of the various mods different cars have. You also can't run an off-the-shelf traction bar because they interfere with the trailing edge of the splitter. In my opinion, that bar is necessary so I modified an existing one I had and it works well. I have an idea that would work for just about everyone, but no need to develop it at this point. It would be significantly more expensive than the plastic cosmetic mods that 99% of Fiesta owners want too.