You might like the results because cutting them in half and putting them in a rib rack will keep the ends away from the outer edge of the cooking grate where it is hotter.
Amen, Jerry. Smoking half slabs of ribs is probably the best tip anyone can give for better ribs on the 18.5".
I bought a couple of large rib racks at Academy which allow me to foil and put the ribs back in it in my 18.5 WSM. I can also bend a whole rack around and put each end in the rack, allowing me to cook two fulls racks vertical on each cooking grid.