About your 7x17. There's no need to go full size or buy extra equipment when you're learning the ropes (or any time for that matter.) I always test one or two 4"x5" plates first in whatever size camera I'm using. If you keep your eyes open, you can find format adapters. Whole plate or 5"x7" to 4"x5" are most common. My 6"x15" pano camera has a 5"x12" reducing inset that I mainly use. To test, I set 4x5 spacers on the left and right sides. This leaves exactly the right size space for a 4x5 plate between them, right in the middle of the focusing area. This lets me test the focus and exposure under the same conditions as I'll use for a full-size plate. I use 4x5-to-quarter plate adapters, but either uncoated glass plates or balsa wood cut to size would work as well.
Best of fun to you,