Also worth a call would be the Big Depot in Leeds who have a much simpler plastic clip on their maillons that is just a horizontal bar that gives more room in the maillon. I tried looking for the design online, but couldn't find anything in google images.
I'll swing by big depot first, as that might be the cheapest option. But the Salewa and Kong gear look like they'll work and I can order both online, so looks like I'll have a solution either way.
I'm very curious as to what requires a mallion that needs crossloading inhibition, but also needs placing and removing frequently... top rope solo set up?