A SMASH allows you to feature a single malt and single hop so that their flavors are not confused with other elements of a recipe.
What you might do is simply take those recipes and wherever it says extra malt, just use whichever one you want to feature. And where there are extra hop choices, just substitute Mosaic.
Pay a little attention to bitterness, but mostly just go with it.
I brew a SMASH that has Maris Otter as the malt, and Styrian Celeia as the hop. It *is* a smash for many that try it. I've been shocked at how many really, *really* like it.
My recipe uses 11# of Maris Otter, and 1.5 oz of StC at 60 minutes, 1.25 oz at 10 minutes, and 1.25 oz at flameout. That hop only has an alpha acid percentage of 2.8%, so yours may be more hoppy or bitter depending on what your Mosaic is.
I use S-04 yeast, rehydrated, with this. I ferment at 64 degrees then when the krausen falls I ramp it up to 71 degrees for a couple days for the yeast to clean up after itself. Then back to 64 for a while, then crash.
Try something like that with your favorite yeast and your malt and hops.