I struggled with this for a while, and here's what I do now.
I typically print on 11x14 FB Matte paper. To make test prints, I use cut-up version of the same paper. I make several 5x7 like size papers out of one large ones and print key areas of the image. Once I know the approximate exposure, I make one full sheet. The result is, then after 2 full sheets worth of paper, I have approximate print. I find any smaller test print didn't help me much, and without a full print at the final size, I can't plan what to do next.
It makes no sense to make test prints on RC for me because sensitivity of emulsion is different, and surface texture affects how the image will look.
There's no other way for me. It just cost more to work with FB. I like the result, so I do it.
Also, buying smaller paper makes no sense either because you'd pay more. It's more economical to buy a large sheet and cut it up for testing.