Make the sauce. Mix the ketchup, vinegar, Dijon mustard, brown sugar, cayenne pepper, salt and black pepper in a bowl. Transfer to a thick-bottomed sauce pot over medium-low heat. Allow the sauce to warm and mix over the heat for 10–15 minutes, stirring throughout. Remove and cool.
Make the spice rub. In a bowl, mix the salt, ground mustard, paprika, black pepper, cayenne pepper, white pepper, seafood seasoning, and cumin together with a spoon. After mixing, keep dry and covered.
Prep the ribs. Remove the silver skin from the bottom side of the ribs. Then, evenly rub each rack with 1⁄4 cup of the spice rub on top and bottom. Wrap each rack in plastic wrap and keep overnight in the refrigerator or cooler.
Heat a smoker with pecan or other fruit wood, bringing it to 165 degrees and maintaining temperature. Once the temperature is obtained, remove the plastic and place the ribs in the smoker for 4 hours, keeping for doneness at this point. The ribs should be cooked, but not falling off the bone.
Remove ribs from smoker and glaze each rack with 1⁄2 cup of BBQ sauce. Then, return to the smoker for 30–40 min. Remove and glaze with additional 1⁄2 cup sauce and finish for a final 20 min. Remove ribs from smoker, allow to rest for 5 min., then cut into single or double bone sections and serve.