Are you planning on using F-line function carriers with your 7x17? I would think they are strong enough for 7x17. They would probably qualify as strength-to-weight champions in that configuration.
I am assembling a 14x20 camera (deardorff back) on a sinar rail based system. I shelved the project for long period but my new year's resolution is to finish it by the end of the summer. I recently picked up a sinar 8x10 c2 (p2 rear/f2 front) to use as the base. I will use a sinar camera support that mates a p/p2 bearer to a camera socket. The camera support has 3 holes that can be used to mount it to a mahogany frame that I made to hold the back.
I think using a sinar has some advantages over the arca for larger cameras and that is why I went this way. I had seen Dave's corona/sinar conversion at Michael & Paula's workshop and it is a practical camera.